Taking a domestic MGKF1800-type high-precision and high-efficiency vertical composite grinding machine as the analysis object, the fault tree analysis method, simulation analysis of simulated operating conditions and numerical model simulation method were introduced to find the weak parts which were most prone to cause faults with the grinding machine. The results show that the root cause of the fault is the low heat dissipation efficiency of the wire guide rail.To address this issue,the thermal deformation of key components of the grinder can be reduced by optimizing structural design, increasing air heat dissipation and rationally allocating external cooling device.By using finite element analysis and reliability evaluation,the specific position and amount of thermal deformation of the grinding machine can be refined，which provides reference for the thermal design and structural optimization design of key components in the actual mass production stage.