Chinese-language agents
Applications that need a Baidu model for multi-step planning, tool selection, search, and Chinese business workflows.
Independent tool overview
ERNIE 5.1 at a glance
ERNIE 5.1 is Baidu's current flagship ERNIE chat model and a Qianfan text-generation endpoint focused on agent tasks, reasoning, deep search, knowledge, and creative writing. It is a more compact successor derived from ERNIE 5.0, with a 128K context window and lower published China API rates than 5.0, but its international Qianfan availability and USD pricing are not yet listed on the current English catalog.
Visit the official ERNIE 5.1 site ↗
- Developer endpoint
- ernie-5.1 on mainland China Qianfan
- Product position
- Current flagship ERNIE chat and text model
- API context
- 128K tokens; up to 119K input
- Maximum API output
- 65,536 tokens
- Default API limit
- 60 RPM and 150K TPM
- Published China price
- From ¥4/M input and ¥18/M output tokens
- Last reviewed
- August 31, 2026
Overview
What ERNIE 5.1 is
Baidu released ERNIE 5.1 in May 2026 as the latest model in its consumer chat experience. It extracts a smaller network from ERNIE 5.0's elastic training foundation: Baidu says total parameters are about one-third and active parameters about one-half of 5.0, while pre-training used roughly 6% of the compute of comparable models. That is a vendor training-efficiency claim, not a 94% reduction in the price customers pay.
The mainland China Qianfan catalog lists `ernie-5.1` with 128K context, up to 119K input tokens, up to 65,536 output tokens, and default limits of 60 requests and 150,000 tokens per minute. Its current placement is under flagship text generation; developers should not assume it exposes the native image, audio, and video capabilities associated with ERNIE 5.0's research architecture.
Baidu emphasizes tool use, multi-step agent behavior, reasoning, deep search, world knowledge, and creative writing. The Qianfan API supports function-calling responses, but the model does not execute functions itself: the application must validate the requested function and arguments, enforce authorization, execute the tool, and safely return the result.
Baidu's leaderboard and internal benchmark comparisons should guide testing rather than decide procurement. Teams should evaluate 5.1 on private Chinese and multilingual tasks, long-context retrieval, tool-call accuracy, factuality, latency, and total cost. Consequential medical, legal, financial, employment, or safety decisions require authoritative sources and accountable human review.
Use cases
Who ERNIE 5.1 is best for
The strongest fit depends on the job you need the product to complete, not the size of its feature list.
Knowledge and creative work
Teams evaluating a current Chinese flagship for research synthesis, long-form writing, document questions, and instruction following.
Mainland China Qianfan users
Developers who can use Baidu's domestic cloud service and benefit from its published yuan pricing and OpenAI-compatible access patterns.
Capabilities
Core ERNIE 5.1 features
Agent-oriented post-training
Baidu trained 5.1 for long-horizon tasks, tool use, autonomous planning, and stability on complex edge cases.
Deep search and knowledge
The release emphasizes search, broad knowledge, reasoning, and synthesis, which should be tested with source-quality and citation checks.
Creative writing
Baidu tuned the model for intent, narrative control, style adaptation, and longer creative outputs.
Function calling
The Qianfan API can return a requested function name and arguments; the host application remains responsible for safe execution.
Long-context text generation
The documented endpoint supports 128K context, 119K maximum input, and up to 65,536 output tokens.
More efficient 5.0 derivative
The model inherits ERNIE 5.0 knowledge from an elastically trained sub-network while using materially fewer total and active parameters.
Process
How the ERNIE 5.1 workflow works
Step 1
Confirm region and access
Check whether the workload can use mainland Qianfan, which identity and payment requirements apply, and whether data location and contract terms meet policy.
Step 2
Create a decision-grade benchmark
Test representative Chinese and multilingual prompts, long documents, search questions, tool calls, refusals, and known failure cases against expected answers.
Step 3
Integrate with least privilege
Keep keys server-side, cap tokens and spend, validate structured output, allowlist functions, constrain arguments, and require authorization before side effects.
Step 4
Measure the full system
Track answer quality, retrieval and citation accuracy, tool-call success, latency, cost, refusal behavior, and human correction—not just model benchmark scores.
Step 5
Pilot and retain rollback
Start with low-impact traffic, log model versions and tool actions, add human escalation, and preserve the ability to fall back to ERNIE 5.0 or another provider.
Cost
ERNIE 5.1 pricing and free plan
Baidu's mainland China Qianfan price sheet lists ERNIE 5.1 by input length. For requests up to 32K input tokens, rates are ¥0.004 per thousand input tokens and ¥0.018 per thousand output tokens—equivalent to ¥4 and ¥18 per million. For inputs above 32K and up to 128K, rates rise to ¥0.006 and ¥0.022 per thousand—¥6 and ¥22 per million. The current international Qianfan catalog lists ERNIE 5.0 but not 5.1, so do not assume these yuan rates or availability apply to an international account.
Qianfan API — input up to 32K
¥4 input / ¥18 output per 1M tokens
Mainland China online-inference pricing for ERNIE 5.1 with shorter inputs.
- Metered pay-as-you-go
- Published as ¥0.004 and ¥0.018 per thousand tokens
- Output tokens are charged at the output rate
- Taxes, promotions, and account terms may differ
Qianfan API — input above 32K to 128K
¥6 input / ¥22 output per 1M tokens
Higher mainland China rate for long-context ERNIE 5.1 requests.
- Published as ¥0.006 and ¥0.022 per thousand tokens
- Model limit is 128K total context with up to 119K input
- Control retrieved context and output length to limit spend
ERNIE consumer chat
No clear English plan price published
Baidu directs users to its ERNIE chat experience but the English release does not publish a dedicated 5.1 subscription price.
- Account and regional access may be required
- Confirm current limits and paid benefits inside the service
- Do not infer API entitlement from consumer chat access
Pricing checked . Check current pricing at the source ↗
Assessment
ERNIE 5.1 strengths and limitations
Where it stands out
- Current Baidu flagship with a strong focus on Chinese knowledge, writing, search, reasoning, and agent workflows
- Lower published mainland China token rates than ERNIE 5.0 for both short- and long-context requests
- Large input and output allowances support document-heavy and multi-step applications
- Function calling and an OpenAI-compatible integration pattern reduce application plumbing for experienced teams
What to consider
- The current English international Qianfan model list and price page do not yet list ERNIE 5.1, creating regional availability and procurement uncertainty
- Baidu's 6% pre-training-compute claim is not the same as a customer price reduction or a measured inference-efficiency guarantee
- The public Qianfan placement is text generation; do not attribute all of ERNIE 5.0's multimodal research capabilities to the 5.1 API endpoint
- Published benchmark and leaderboard comparisons can change and may not predict private workload quality
- Use outside China may involve language, support, billing, regulatory, data-transfer, and account-access considerations that require legal and security review
Compare
ERNIE 5.1 alternatives
The right alternative depends on the specific output, workflow, controls and budget your project requires.
Consumer
ERNIE 5.0
Choose ERNIE 5.0 when international Qianfan availability, multimodal visual understanding, or compatibility with an existing endpoint matters more than using Baidu's newest model.
Explore ERNIE 5.0 →Consumer
Qwen3-Max-Thinking
Consider Qwen3-Max-Thinking for another Chinese flagship focused on reasoning and agentic work in Alibaba's ecosystem.
Explore Qwen3-Max-Thinking →Business Operations
DeepSeek
Consider DeepSeek for alternative Chinese reasoning models, broader open-model options, or different API economics.
Explore DeepSeek →Questions
ERNIE 5.1 FAQs
What is ERNIE 5.1?
ERNIE 5.1 is Baidu's current flagship ERNIE model for chat and Qianfan text generation, emphasizing agent tasks, reasoning, deep search, knowledge, and creative writing.
Is ERNIE 5.1 better than ERNIE 5.0?
Baidu positions it as the newer, more compact, and more efficient successor with stronger agent and reasoning behavior. The right choice still depends on regional availability, required modalities, latency, compatibility, and results on the application's own evaluation set.
How much does the ERNIE 5.1 API cost?
On mainland China Qianfan, inputs up to 32K cost ¥4 per million input tokens and outputs cost ¥18 per million. For inputs above 32K to 128K, rates are ¥6 and ¥22 per million. International 5.1 pricing was not published on the current English price page during this review.
What is ERNIE 5.1's context window?
The Qianfan model list gives it a 128K-token context window, up to 119K input tokens, and up to 65,536 output tokens, with default limits of 60 requests and 150,000 tokens per minute.
Can ERNIE 5.1 execute tools?
It can propose function calls, but the API does not execute them. Your application must validate the model's function name and arguments, check user authorization, run the tool, and handle the result safely.
Is ERNIE 5.1 safe for legal, medical, or financial advice?
It should not be the final decision-maker. Require authoritative sources, domain-expert review, privacy controls, and explicit accountability for any consequential use.
Bottom line
Our ERNIE 5.1 verdict
ERNIE 5.1 is the Baidu model new China-focused projects should benchmark first: it is current, cheaper than 5.0 on the published domestic API, and designed for agent, search, reasoning, and writing workloads. Its main caveat is distribution rather than inactivity—the model is clearly live in China, while current English Qianfan documentation has not caught up with international access or USD pricing. Confirm region, contract, and exact endpoint capabilities before committing.
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