---

DeepSeek-V3.1 is a hybrid model that supports both thinking mode and non-thinking mode. Compared to the previous version, this upgrade brings improvements in multiple aspects:

• Hybrid thinking mode: One model supports both thinking mode and non-thinking mode by changing the chat template.

• Smarter tool calling: Through post-training optimization, the model's performance in tool usage and agent tasks has significantly improved.

• Higher thinking efficiency: DeepSeek-V3.1-Think achieves comparable answer quality to DeepSeek-R1-0528, while responding more quickly.

DeepSeek-V3.1 is post-trained on the top of DeepSeek-V3.1-Base, which is built upon the original V3 base checkpoint through a two-phase long context extension approach, following the methodology outlined in the original DeepSeek-V3 report. We have expanded our dataset by collecting additional long documents and substantially extending both training phases. The 32K extension phase has been increased 10-fold to 630B tokens, while the 128K extension phase has been extended by 3.3x to 209B tokens. Additionally, DeepSeek-V3.1 is trained using the UE8M0 FP8 scale data format to ensure compatibility with microscaling data formats.

The details of our chat template is described in tokenizer_config.json and assets/chat_template.jinja. Here is a brief description.

Prefix: <｜begin▁of▁sentence｜>{system prompt}<｜User｜>{query}<｜Assistant｜></think>

With the given prefix, DeepSeek V3.1 generates responses to queries in non-thinking mode. Unlike DeepSeek V3, it introduces an additional token </think>.

Context: <｜begin▁of▁sentence｜>{system prompt}<｜User｜>{query}<｜Assistant｜></think>{response}<｜end▁of▁sentence｜>...<｜User｜>{query}<｜Assistant｜></think>{response}<｜end▁of▁sentence｜>

Prefix: <｜User｜>{query}<｜Assistant｜></think>

By concatenating the context and the prefix, we obtain the correct prompt for the query.

Prefix: <｜begin▁of▁sentence｜>{system prompt}<｜User｜>{query}<｜Assistant｜><think>

The prefix of thinking mode is similar to DeepSeek-R1.

Context: <｜begin▁of▁sentence｜>{system prompt}<｜User｜>{query}<｜Assistant｜></think>{response}<｜end▁of▁sentence｜>...<｜User｜>{query}<｜Assistant｜></think>{response}<｜end▁of▁sentence｜>

Prefix: <｜User｜>{query}<｜Assistant｜><think>

The multi-turn template is the same with non-thinking multi-turn chat template. It means the thinking token in the last turn will be dropped but the </think> is retained in every turn of context.

Toolcall is supported in non-thinking mode. The format is:

<｜begin▁of▁sentence｜>{system prompt}{tool_description}<｜User｜>{query}<｜Assistant｜></think> where the tool_description is

## Tools
You have access to the following tools:

### {tool_name1}
Description: {description}

Parameters: {json.dumps(parameters)}

IMPORTANT: ALWAYS adhere to this exact format for tool use:
<｜tool▁calls▁begin｜><｜tool▁call▁begin｜>tool_call_name<｜tool▁sep｜>tool_call_arguments<｜tool▁call▁end｜>{{additional_tool_calls}}<｜tool▁calls▁end｜>

Where:
- `tool_call_name` must be an exact match to one of the available tools
- `tool_call_arguments` must be valid JSON that strictly follows the tool's Parameters Schema
- For multiple tool calls, chain them directly without separators or spaces

We support various code agent frameworks. Please refer to the above toolcall format to create your own code agents. An example is shown in assets/code_agent_trajectory.html.

We design a specific format for searching toolcall in thinking mode, to support search agent.

For complex questions that require accessing external or up-to-date information, DeepSeek-V3.1 can leverage a user-provided search tool through a multi-turn tool-calling process.

Please refer to the assets/search_tool_trajectory.html and assets/search_python_tool_trajectory.html for the detailed template.

Category	Benchmark (Metric)	DeepSeek V3.1-NonThinking	DeepSeek V3 0324	DeepSeek V3.1-Thinking	DeepSeek R1 0528
General
	MMLU-Redux (EM)	91.8	90.5	93.7	93.4
	MMLU-Pro (EM)	83.7	81.2	84.8	85.0
	GPQA-Diamond (Pass@1)	74.9	68.4	80.1	81.0
	Humanity's Last Exam (Pass@1)	-	-	15.9	17.7
Search Agent
	BrowseComp	-	-	30.0	8.9
	BrowseComp_zh	-	-	49.2	35.7
	Humanity's Last Exam (Python + Search)	-	-	29.8	24.8
	SimpleQA	-	-	93.4	92.3
Code
	LiveCodeBench (2408-2505) (Pass@1)	56.4	43.0	74.8	73.3
	Codeforces-Div1 (Rating)	-	-	2091	1930
	Aider-Polyglot (Acc.)	68.4	55.1	76.3	71.6
Code Agent
	SWE Verified (Agent mode)	66.0	45.4	-	44.6
	SWE-bench Multilingual (Agent mode)	54.5	29.3	-	30.5
	Terminal-bench (Terminus 1 framework)	31.3	13.3	-	5.7
Math
	AIME 2024 (Pass@1)	66.3	59.4	93.1	91.4
	AIME 2025 (Pass@1)	49.8	51.3	88.4	87.5
	HMMT 2025 (Pass@1)	33.5	29.2	84.2	79.4

Note:

• Search agents are evaluated with our internal search framework, which uses a commercial search API + webpage filter + 128K context window. Seach agent results of R1-0528 are evaluated with a pre-defined workflow.

• SWE-bench is evaluated with our internal code agent framework.

• HLE is evaluated with the text-only subset.

import transformers

tokenizer = transformers.AutoTokenizer.from_pretrained("deepseek-ai/DeepSeek-V3.1")

messages = [
    {"role": "system", "content": "You are a helpful assistant"},
    {"role": "user", "content": "Who are you?"},
    {"role": "assistant", "content": "<think>Hmm</think>I am DeepSeek"},
    {"role": "user", "content": "1+1=?"}
]

tokenizer.apply_chat_template(messages, tokenize=False, thinking=True, add_generation_prompt=True)
# '<｜begin▁of▁sentence｜>You are a helpful assistant<｜User｜>Who are you?<｜Assistant｜></think>I am DeepSeek<｜end▁of▁sentence｜><｜User｜>1+1=?<｜Assistant｜><think>'

tokenizer.apply_chat_template(messages, tokenize=False, thinking=False, add_generation_prompt=True)
# '<｜begin▁of▁sentence｜>You are a helpful assistant<｜User｜>Who are you?<｜Assistant｜></think>I am DeepSeek<｜end▁of▁sentence｜><｜User｜>1+1=?<｜Assistant｜></think>'

The model structure of DeepSeek-V3.1 is the same as DeepSeek-V3. Please visit DeepSeek-V3 repo for more information about running this model locally.

This repository and the model weights are licensed under the MIT License.

@misc{deepseekai2024deepseekv3technicalreport,
      title={DeepSeek-V3 Technical Report}, 
      author={DeepSeek-AI},
      year={2024},
      eprint={2412.19437},
      archivePrefix={arXiv},
      primaryClass={cs.CL},
      url={https://arxiv.org/abs/2412.19437}, 
}

If you have any questions, please raise an issue or contact us at service@deepseek.com.