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MiMo-V2.6-Flash-RL

Scaling Reinforcement Learning Toward Self-Improvement

Technical Report

1. Introduction

MiMo-V2.6-Flash-RL is the efficiency-balanced checkpoint of the MiMo-V2.6 series. The series is built to scale reinforcement learning toward self-improvement — scaling RL compute, environment diversity, and grader compute together, so the model keeps expanding its capability frontier through exploration and feedback. Key features include:

  • Native Omnimodal + Long Horizon: Text, image, video, and audio in one model; 1M tokens for long repositories, tool traces, and multi-session agent runs.
  • You Only RL Once: One mixed RL run across coding, general agents, visual, and cybersecurity — not separate per-domain runs. Tasks and multiple harnesses are mixed in the same batch so capabilities reinforce each other and strategies transfer to harnesses never seen in training.
  • Scaling RL Compute: Fully asynchronous Group Relative Policy Optimization (GRPO) on very large batches — 1,568 prompts × 16 rollouts per step, billions of tokens per update.
  • Groupwise Agentic Grading (Self-Improvement Loop): Binary pass/fail cannot rank passing solutions, so the reward signal itself is scaled. An agentic grader compares rollouts within each group: Groupwise Reward Synthesis (GRS) builds task-specific rubrics offline from contrasting rollouts and fuses rubric quality with test outcomes; Groupwise Advantage Redistribution (GAR) ranks passing trajectories online and moves advantage toward higher-quality solutions. Judged against the policy’s own samples, this closes a self-improvement loop and steers toward shorter paths and fewer tokens per task.
  • Aligned RL: Cold start from self-correction — the model reflects on and rewrites its own misaligned turns into grounded next steps. Throughout RL, environment hardening, adversarial screening, and verifier cross-checks keep the loop honest against reward hacking.
  • Multi-Prefix Multi-Teacher On-Policy Distillation (MOPD2): After mixed RL, MOPD2 combines autonomous student rollouts with prefix-conditioned single-turn rollouts (Teacher-Prefix and SFT-Prefix), reusing histories from teacher trajectories and SFT demonstrations so decision points train without regenerating preceding turns — extending capabilities to hard-to-verify tasks.

Model Summary

  • Architecture: Sparse MoE (Mixture of Experts), 309B total / 15B activated parameters
  • Context Length: 1M tokens
  • Modalities: Text, Image, Video, Audio
  • Vision Encoder: 681M-param MiMo ViT (28 layers: 24 SWA + 4 Full)
  • Audio Encoder: 308M AudioTokenizer + 127M audio patch encoder
  • Multi-Token Prediction (MTP): 5-layer speculative decoder

Figure 1: MiMo-V2.6 architecture — omni encoders, hybrid SWA backbone, and MTP blocks

Figure 1. MiMo-V2.6 architecture.

2. Downloads

Model Download
MiMo-V2.6-Pro-RL 🤗 HuggingFace · 🤖 ModelScope
MiMo-V2.6-Flash-RL 🤗 HuggingFace · 🤖 ModelScope

3. Evaluation Results

Benchmark MiMo-V2.6 Pro MiMo-V2.6 Flash MiMo-V2.5 Pro Claude Opus 5 GPT-5.6 Sol Claude Fable 5
Code Agent
DeepSWE v1.1 71.9 67.9 19.0 74.0 73.0 70.0
ProgramBench 26.5 26.0 12.5 37.0 25.0 33.0
MiMo Code Bench 63.2 61.2 40.4 68.6 59.3 -
General Agent
AutomationBench v1.0.6 53.1 52.3 16.0 50.3 45.8 46.2
Toolathlon-Verified 76.9 73.6 49.1 80.6 74.9 77.9
GDPval-AA 2.1 1673 - 1107 1708 1588 1595
Agents’ Last Exam 31.6 27.6 13.2 31.6 30.8 25.7
Terminal Bench 4.0 34.9 28.8 1.5 49.0 39.9 42.4
Terminal Bench 2.1 89.9 87.6 65.2 89.1 88.8 84.3
OSWorld-Verified 82.0 80.8 - 83.4 83.0 86.0
JobBench 62.0 61.2 25.0 65.7 45.4 57.4
Cybersecurity
CyberGym 94.0 95.1 40.0 - - -
MiMo Cyber Bench 80.2 77.2 0.0 - - -
ExploitGym 17.8 6.0 0.2 22.1 30.3 28.4
ExploitBench 47.9 25.3 16.6 70.0 78.5 78.0
SEC Bench Pro 66.3 47.5 17.7 - 79.1 -
Visual Agent
MiMo VisualCoding 72.3 71.5 - 70.0 73.4 69.1

4. Model Architecture

LLM Backbone

Component MiMo-V2.6-Flash-RL
Layers (Total / SWA / GA) 48 / 39 / 9
Hidden Size 4096
SWA Heads (Q/KV) 64 / 8
GA Heads (Q/KV) 64 / 4
Head Dimensions (QK / V) 192 / 128
Sliding Window Size 128
Routed Experts (Total / Activated) 256 / 8
Max Context Length 1M
MTP / Speculative Decoder 5 SWA layers, window 1024

The first Transformer block uses global attention with a dense FFN. Remaining blocks interleave local SWA and GA; both use sparse MoE FFNs without shared experts.

Vision Encoder (MiMo ViT)

Configuration Value
Layers (Total / SWA / GA) 28 / 24 / 4
Hidden Size 1280
Attention Heads (Q / KV) 32 / 8
Head Dimension 64
Patch Size (T × H × W) 2 × 16 × 16
Sliding Window (Left / Right) 64 / 64
Spatial Merge Size 2 × 2
Parameters 681M

Audio Encoders

AudioTokenizer encoder: 24 layers (12 SWA / 12 GA), hidden 1024, 20 RVQ codebooks, 308M parameters. Audio patch encoder: 6 layers, 127M parameters; four frames per patch (25 Hz → 6.25 Hz).

Speculative Decoder

5-layer SWA MTP drafter (DFlash-style). Predicts 7 subsequent tokens per forward pass for parallel verification.

5. Deployment

For best performance, follow the SGLang MiMo cookbook. Docker image: lmsysorg/sglang:latest.

SGLang

sglang serve \
  --trust-remote-code \
  --model-path XiaomiMiMo/MiMo-V2.6-Flash-RL \
  --tp 8 \
  --dp 2 \
  --enable-dp-attention \
  --enable-dp-lm-head \
  --mm-enable-dp-encoder \
  --mem-fraction-static 0.65 \
  --chunked-prefill-size 16384 \
  --speculative-algorithm EAGLE \
  --speculative-num-steps 3 \
  --speculative-eagle-topk 1 \
  --speculative-num-draft-tokens 4 \
  --enable-multi-layer-eagle \
  --reasoning-parser mimo \
  --tool-call-parser mimo \
  --host 0.0.0.0 \
  --port 30000

vLLM

Follow the vLLM MiMo-V2.5 recipe. Stable vLLM may lag; pre-built image: docker pull vllm/vllm-openai:mimov25-cu129.

vllm serve XiaomiMiMo/MiMo-V2.6-Flash-RL \
  --tensor-parallel-size 4 \
  --trust-remote-code \
  --gpu-memory-utilization 0.95 \
  --max-model-len auto \
  --reasoning-parser mimo \
  --tool-call-parser mimo \
  --enable-auto-tool-choice \
  --generation-config vllm

Recommended sampling: temperature=1.0, top_p=0.95.

Also available in AI Studio, MiMo Code, Xiaomi MiMo Desktop, Xiaomi MiMo Open Platform API, and OpenRouter.

Citation

@misc{mimo2026v26flash,
  title={MiMo-V2.6-Flash-RL},
  author={{Xiaomi MiMo Team}},
  year={2026},
  howpublished={\url{https://huggingface.co/XiaomiMiMo/MiMo-V2.6-Flash-RL}},
}

Contact

For questions or feedback, reach us at mimo@xiaomi.com or join our community:

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