Meituan's LongCat team open-sourced LongCat-Flash-Prover on March 21st, a 560 billion parameter MoE model focused on Lean4 formal theorem proving. The model comprises three capabilities: automatic formalization, sketch generation, and complete proof generation, combined with reasoning tools and the Lean4 compiler to achieve real-time verification. Training utilizes the Hybrid-Experts Iteration Framework and HisPO algorithm to prevent reward hacking. Benchmark results show that the model sets new records for open-source weight models in automatic formalization and theorem proving.