Qwen3.5-4B

Qwen

Parameters

4.0B

Architecture

Causal Language Model with Vision Encoder - Hybrid Gated Delta Networks + Gated Attention (dense FFN)

Released

27.02.2026

License

Apache License 2.0

Open Weights Commercial Use Multimodal BF16 Qwen3.5 en zh 201 languages

Input Modalities

text image video

Output Modalities

text

Context (native)

262,144 tokens

Context (extended)

1,010,000 tokens

Openness Index Score 100.0/100

About

Qwen3.5-4B (Qwen/Qwen3.5-4B) is the small dense member of Alibaba's Qwen3.5 generation - a unified vision-language foundation model with 4B parameters handling text, image and video input in 201 languages and dialects, trained with Early fusion (multimodal pre-training) on multimodal tokens and post-trained with RL scaled across million-agent RL environments.

Its 32-layer hybrid layout repeats 8x (3x (Gated DeltaNet -> FFN) + 1x (Gated Attention -> FFN)): 24 linear-attention layers (Gated DeltaNet with 32 V / 16 QK heads, head dim 128) and 8 full-attention layers (Gated Attention with 16 Q / 4 KV heads, head dim 256, RoPE dim 64), with hidden size 2560, dense FFN 9216 (no MoE), 248K vocabulary tied to token embeddings, and Multi-Token Prediction (MTP) trained with multi-steps. Context is 262,144 tokens natively, extensible up to 1,010,000 tokens.

As a Qwen3.5 family member it delivers the generation's agentic capabilities (native function calling, thinking-mode control via enable_thinking) in a single-GPU-sized package, outperforming much larger Qwen3-VL models across reasoning, coding, agents and visual understanding. Released February 27, 2026 under Apache 2.0.

Training Data Pre-trained on multimodal tokens with early fusion. Post-trained with RL across million-agent environments. 201 languages and dialects.

Benchmark Scores

Benchmark Score Date Standing
LVBench
video_understanding
71.19%
01.02.2026
#8/12
better than 36%
ScreenSpot Pro
general_agent
60.40%
01.02.2026
#9/11
better than 20%
OSWorld-Verified
general_agent
35.60
01.02.2026
#25/25
better than 0%
AndroidWorld
general_agent
58.60
01.02.2026
#13/13
better than 0%
TIR-Bench
vision_language
40.62%
01.02.2026
#4/8
better than 57%
V-Star
vision_language
64.57%
01.02.2026
#15/20
better than 26%
SLAKE
vision_language
79.55%
01.02.2026
#4/8
better than 57%
PMC-VQA
vision_language
71.11%
01.02.2026
#5/8
better than 43%
MedXpertQA-MM
vision_language
44.29%
01.02.2026
#10/13
better than 25%
ParseBench Mean
document_understanding
35.40
01.02.2026
#3/3
better than 0%

Architecture

Decoder Block ×32 input Embedding vocab 248K · d 2560 Linear / Recurrent Hybrid 16:4 · dₕ 256 ×24 Full Attention Hybrid 16:4 · dₕ 256 ×8 Dense FFN silu · d 9216 Final Norm LM Head tied with embedding output
Attention
Hybrid Attention (16:4)
Layers
32
Hidden size
2560
Context
262K tokens
Parameters
4000M

Source: Hugging Face config.json · Qwen3_5ForConditionalGeneration · exact layer pattern · model repo

Type: Hybrid Gated Delta Networks + Gated Attention (dense)
Attention: Gated Attention with RoPE (16 Q heads, 4 KV heads, head_dim=256, RoPE dim=64) + Gated DeltaNet linear attention (32 V heads, 16 QK heads, head_dim=128)
Decoder: Causal Language Model
Routing: sparse
Lm Output

248K

Lm Output Note

tied to token embedding

Token Embedding

248K

Token Embedding Note

padded

Training Pipeline

  1. 1
    pretraining

    Pre-training with Multimodal Early Fusion

    Pre-training on multimodal tokens with early fusion. Near-100% multimodal training efficiency compared to text-only training. 201 languages and dialects supported.

  2. 2
    rl

    Reinforcement Learning Post-training

    Post-training with reinforcement learning scaled across million-agent environments with progressively complex task distributions for robust real-world adaptability. Asynchronous RL frameworks supporting massive-scale agent scaffolds and environment orchestration.

  3. 3
    other

    Post-training (Thinking + Instruct Modes)

    Post-training stage producing the final model weights compatible with Hugging Face Transformers, vLLM, SGLang, KTransformers. Includes thinking mode and instruct mode capabilities.

Training & Evaluation Datasets

NameRoleSizeModalitiesCollection
Early-fusion multimodal token corpus (text + image) pretraining — —
Million-agent RL task environments rl — —

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