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MiMo V2 Flash

Active Parameters

15B

Context Length

256K

Modality

Text

Architecture

Mixture of Experts (MoE)

License

MIT

Release Date

10 Dec 2025

Knowledge Cutoff

Dec 2024

System Requirements

VRAM requirements for different quantization methods and context sizes

1,024 tokens

33.21 GB VRAM

Consumer

2x RTX 4090

24GB VRAM

Datacenter

1x NVIDIA A100

80GB VRAM

Apple Silicon

1x Apple M3 Max

128GB VRAM

256,000 tokens

85.85 GB VRAM

Consumer

4x RTX 4090

24GB VRAM

Datacenter

2x NVIDIA A100

80GB VRAM

Apple Silicon

1x Apple M3 Max

128GB VRAM

Architecture Diagram

Input TokensToken EmbeddingPosition: AbsoluteHidden: 4.1k · Context: 256K · Vocab: 151.7kx 48 layersRMSNormPre-AttentionMulti-Head Attention64Q / 8KV headsHead dim: 128+RMSNormPre-FFNSparse MoE FFN (8/256 experts)SwiGLU+Final RMSNormOutput Logits

Evaluation Benchmarks

Rank

#96

BenchmarkScoreRank

Graduate-Level QA

GPQA

0.837

15

Web Development

WebDev Arena

1330

72

General Text

Text Arena

1393

88

Rankings

Overall Rank

#96

Coding Rank

#75

About MiMo V2 Flash

The Xiaomi MiMo V2 Flash is a high-efficiency Mixture-of-Experts (MoE) language model engineered for advanced reasoning, software engineering, and autonomous agentic workflows. Built upon a sparse architecture, the model incorporates a total of 309 billion parameters while activating only 15 billion parameters per forward pass, effectively balancing the modeling capacity of a large-scale system with the inference speed and operational efficiency of a significantly smaller dense model. Its development focus centers on high-throughput performance, achieving high decoding speeds through structural innovations designed to alleviate the computational and memory bottlenecks typically associated with large-scale transformer models.

Technically, MiMo V2 Flash introduces a hybrid attention mechanism that interleaves Sliding Window Attention (SWA) and Global Attention (GA) in a 5:1 ratio across its transformer blocks. This configuration utilizes an aggressive 128-token sliding window, which reduces KV-cache memory requirements by nearly six-fold compared to standard global attention, while a learnable attention sink bias ensures stable long-context performance. Furthermore, the model features a native Multi-Token Prediction (MTP) module consisting of lightweight 0.33 billion parameter dense feed-forward blocks. This MTP architecture facilitates parallel token generation and verification, resulting in a reported increase in decoding throughput by 2.0 to 2.6 times relative to conventional autoregressive generation methods.

Pre-trained on a massive 27 trillion token corpus using FP8 mixed precision, MiMo V2 Flash supports a native sequence length of 32,000 tokens and is capable of handling context windows up to 256,000 tokens. The post-training phase utilizes a novel Multi-Teacher On-Policy Distillation (MOPD) paradigm and large-scale reinforcement learning, specifically targeting complex reasoning and multi-step tool use. This specialized training enables the model to perform reliably in demanding technical scenarios, such as document analysis and extended agentic interactions, making it a resource-optimized solution for researchers and developers requiring state-of-the-art performance in open-weight formats.

Technical Specifications

Attention

Attention Structure

Multi-Head Attention

Attention Heads

64

Key-Value Heads

8

Attention Head Dimension

128

Position Embedding

Absolute Position Embedding

RoPE Theta

640,000

Sliding Window Attention

No

Sliding Window Size

-

Sliding Window Ratio

-

Linear Attention

-

Linear Attention Ratio

-

Normalization

RMS Normalization

Activation Function

SwigLU

Dimensions

Hidden Dimension Size

4,096

Number of Layers

48

FFN Intermediate Size (Dense)

11,008

Multi-Token Prediction Heads

1

Tokenizer

Vocabulary Size

151,680

Mixture of Experts

Total Expert Parameters

309.0B

Number of Experts

256

Active Experts

8

Shared Experts

-

FFN Intermediate Size (per Expert)

-

Dense Layers Before MoE

-

About MiMo V2

MiMo-V2-Flash is a Mixture-of-Experts (MoE) model with hybrid attention architecture designed for high-speed reasoning and agentic workflows. It features Multi-Token Prediction (MTP) to achieve state-of-the-art performance while significantly reducing inference costs. The model is optimized for long-context modeling and efficient inference.


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