Abstract: In order to study the failure mechanism of surrounding rock of TBM assembly chamber in deep coal mine and optimize its support scheme, taking the construction of TBM assembly chamber in Zhangji Coal Mine as the engineering background, the numerical model of block discrete element method was established, and the numerical simulation was carried out to analyze the deformation and failure mechanism of surrounding rock of TBM assembly chamber. Based on the field monitoring data and numerical simulation results, the deformation and failure mechanism of TBM assembly chamber is revealed, and the optimization scheme of assembly chamber repair and support is adopted, which is mainly composed of full anchor support and hardened floor. The results show that the optimized support scheme of assembly chamber effectively controls the damage and deformation of surrounding rock, and the construction technology is simple, which has little impact on TBM assembly and launching.