LongCat-Flash Technical Report
Abstract
We introduce LongCat-Flash, a 560-billion-parameter Mixture-of-Experts (MoE) language model designed for both computational efficiency and advanced agentic capabilities. Stemming from the need for scalable efficiency, LongCat-Flash adopts two novel designs: (a) Zero-computation Experts, which enables dynamic computational budget allocation and activates 18.6B-31.3B (27B on average) per token depending on contextual demands, optimizing resource usage. (b) Shortcut-connected MoE, which enlarges the computation-communication overlap window, demonstrating notable gains in inference efficiency and throughput compared to models of a comparable scale. We develop a comprehensive scaling framework for large models that combines hyperparameter transfer, model-growth initialization, a multi-pronged stability suite, and deterministic computation to achieve stable and reproducible training. Notably, leveraging the synergy among scalable architectural design and infrastructure efforts, we complete model training on more than 20 trillion tokens within 30 days, while achieving over 100 tokens per second (TPS) for inference at a cost of $0.70 per million output tokens. To cultivate LongCat-Flash towards agentic intelligence, we conduct a large-scale pre-training on optimized mixtures, followed by targeted mid- and post-training on reasoning, code, and instructions, with further augmentation from synthetic data and tool use tasks. Comprehensive evaluations demonstrate that, as a non-thinking foundation model, LongCat-Flash delivers highly competitive performance among other leading models, with exceptional strengths in agentic tasks. The model checkpoint of LongCat-Flash is open-sourced to foster community research. LongCat Chat: https://longcat.ai Hugging Face: https://huggingface.co/meituan-longcat GitHub: https://github.com/meituan-longcat
Cite
@article{arxiv.2509.01322,
title = {LongCat-Flash Technical Report},
author = {Meituan LongCat Team and Bayan and Bei Li and Bingye Lei and Bo Wang and Bolin Rong and Chao Wang and Chao Zhang and Chen Gao and Chen Zhang and Cheng Sun and Chengcheng Han and Chenguang Xi and Chi Zhang and Chong Peng and Chuan Qin and Chuyu Zhang and Cong Chen and Congkui Wang and Dan Ma and Daoru Pan and Defei Bu and Dengchang Zhao and Deyang Kong and Dishan Liu and Feiye Huo and Fengcun Li and Fubao Zhang and Gan Dong and Gang Liu and Gang Xu and Ge Li and Guoqiang Tan and Guoyuan Lin and Haihang Jing and Haomin Fu and Haonan Yan and Haoxing Wen and Haozhe Zhao and Hong Liu and Hongmei Shi and Hongyan Hao and Hongyin Tang and Huantian Lv and Hui Su and Jiacheng Li and Jiahao Liu and Jiahuan Li and Jiajun Yang and Jiaming Wang and Jian Yang and Jianchao Tan and Jiaqi Sun and Jiaqi Zhang and Jiawei Fu and Jiawei Yang and Jiaxi Hu and Jiayu Qin and Jingang Wang and Jiyuan He and Jun Kuang and Junhui Mei and Kai Liang and Ke He and Kefeng Zhang and Keheng Wang and Keqing He and Liang Gao and Liang Shi and Lianhui Ma and Lin Qiu and Lingbin Kong and Lingtong Si and Linkun Lyu and Linsen Guo and Liqi Yang and Lizhi Yan and Mai Xia and Man Gao and Manyuan Zhang and Meng Zhou and Mengxia Shen and Mingxiang Tuo and Mingyang Zhu and Peiguang Li and Peng Pei and Peng Zhao and Pengcheng Jia and Pingwei Sun and Qi Gu and Qianyun Li and Qingyuan Li and Qiong Huang and Qiyuan Duan and Ran Meng and Rongxiang Weng and Ruichen Shao and Rumei Li and Shizhe Wu and Shuai Liang and Shuo Wang and Suogui Dang and Tao Fang and Tao Li and Tefeng Chen and Tianhao Bai and Tianhao Zhou and Tingwen Xie and Wei He and Wei Huang and Wei Liu and Wei Shi and Wei Wang and Wei Wu and Weikang Zhao and Wen Zan and Wenjie Shi and Xi Nan and Xi Su and Xiang Li and Xiang Mei and Xiangyang Ji and Xiangyu Xi and Xiangzhou Huang and Xianpeng Li and Xiao Fu and Xiao Liu and Xiao Wei and Xiaodong Cai and Xiaolong Chen and Xiaoqing Liu and Xiaotong Li and Xiaowei Shi and Xiaoyu Li and Xili Wang and Xin Chen and Xing Hu and Xingyu Miao and Xinyan He and Xuemiao Zhang and Xueyuan Hao and Xuezhi Cao and Xunliang Cai and Xurui Yang and Yan Feng and Yang Bai and Yang Chen and Yang Yang and Yaqi Huo and Yerui Sun and Yifan Lu and Yifan Zhang and Yipeng Zang and Yitao Zhai and Yiyang Li and Yongjing Yin and Yongkang Lv and Yongwei Zhou and Yu Yang and Yuchen Xie and Yueqing Sun and Yuewen Zheng and Yuhuai Wei and Yulei Qian and Yunfan Liang and Yunfang Tai and Yunke Zhao and Zeyang Yu and Zhao Zhang and Zhaohua Yang and Zhenchao Zhang and Zhikang Xia and Zhiye Zou and Zhizhao Zeng and Zhongda Su and Zhuofan Chen and Zijian Zhang and Ziwen Wang and Zixu Jiang and Zizhe Zhao and Zongyu Wang and Zunhai Su},
journal= {arXiv preprint arXiv:2509.01322},
year = {2025}
}