Confucius4 is an open-source multimodal LLM developed by the NetEase Youdao AI Team, built upon the Qwen3.5 architecture and designed for advanced mathematical reasoning. Key features:
✅ 1. Cost-Effective Multimodal Training Set with SFT-RL Iterative Optimization, Achieving SOTA among Comparable-Scale Models
Image-gain filtering is used to eliminate low-value visual redundancy, building a cost-effective multimodal training set.
An iterative SFT + RL paradigm continuously elevates performance across both text-only and multimodal scenarios.
✅ 2. Pure-Text Reasoning Data Augmentation in SFT for Stronger Reasoning Foundation (+23.2% on Math-Hard-500)
Pure-text reasoning data injected during SFT reinforces the multimodal model's reasoning backbone.
A hybrid "text reasoning + multimodal problem-solving" training paradigm achieves synergistic gains between reasoning capability and multimodal perception.
✅ 3. Refined CoT SFT + Length-Aware RL: Achieving Both Accuracy and Efficiency (CoT length reduced by 43.2%)
SFT stage: chain-of-thought reasoning is reconstructed to eliminate redundant steps, producing concise yet complete high-quality chains.
RL stage: a Length-Aware Advantage mechanism introduces an explore-exploit tradeoff into advantage computation, constraining reasoning length for non-challenging problems and effectively eliminating overthinking.
Additionally, through targeted optimization on Chinese-language data, Confucius4 produces outputs that are more aligned with the linguistic habits, cultural context, and expression preferences of Chinese-speaking users.
3 Performance
Benchmark
Confucius3-Math
Qwen3.5-27B
Qwen3.5-35B-A3B
Qwen3.6-27B
Confucius4
Math-Hard-500
0.626
0.582
0.614
0.756
0.814
Math-Figure
-
0.866
0.834
0.865
0.907
MathVision (testmini)
-
0.651
0.625
0.648
0.724
logicVista
-
0.734
0.741
0.743
0.779
MathVerse
-
0.866
0.859
0.865
0.876
MathVista (testmini)
-
0.874
0.864
0.871
0.874
DynaMath
-
0.877
0.889
0.856
0.893
We-Math
-
0.913
0.906
0.907
0.912
Notes:
Math-Figure is an internally collected, proprietary multimodal problem-solving dataset (664 samples).
Math-Hard-500 is a proprietary dataset focusing on challenging middle and high school problems, including a subset of competition-level questions (500 samples).
Confucius3-Math is a text-only model, therefore only evaluated on Math-Hard-500.
4 Inference
The environmental requirements for running Confucius4 are exactly the same as those of the Qwen3.5 model. Therefore, you can easily use Transformers or vLLM to load and run the model for inference, and deploy your services.
The only thing you need to pay attention to is to use the predefined system message and user message templates provided below to request the model. Other templates may also be usable, but we haven't tested them yet.
SYSTEM_PROMPT_TEMPLATE = """You are a helpful assistant."""
Then you can create your messages as follows and use them to request model results. For multimodal input, encode the image as base64 and include it alongside the text question.
Significant thanks to the ms-swift team for providing an efficient and scalable fine-tuning framework that greatly facilitated the training of this model. We also acknowledge the Qwen team for their foundational models.
Model Declaration
This project is fine-tuned and optimized based on Qwen3.5-27B.
License
This project is released under the Apache License 2.0.
Free for commercial use, modification, and distribution
Modified versions must indicate the changes made
Derivative works must retain the original open-source notice
Citation
If you find our work helpful, feel free to give us a cite.
@misc{confucius4,
title = {Confucius4: Advancing Multimodal Reasoning with Iterative SFT-RL Optimization and Compact Chain-of-Thought},
author = {NetEase Youdao AI Team},
year = {2026},
publisher = {Hugging Face},
howpublished = {\url{https://huggingface.co/netease-youdao/Confucius4}}
}