High-end CNC machine tools represented by five-axis machining centers are important national strategic materials and have high comprehensive performance requirements.The structural characteristics of movable crossrail bearing rotary milling head in horizontal machining were investigated based on thermal-solid coupling analysis method.A solid finite element model of the movable crossrail was established for thermal-solid coupling simulation,and the deformation and stress of the movable crossrail were analyzed under the comprehensive effects of structural static load and thermal load.The multiple regression fitting method was used to study the influence law of structural parameters on the structural characteristics of the movable crossrail,and the structural parameters were optimized according to the influence law.After optimization,the maximum deformation of the movable crossrail along the Y axis is reduced by 10.489% and the maximum stress is reduced by 41.06% with the basically same quality.