Bolt connection is widely used in mechanical and electrical manufacturing industry because of its unique structure and performance characteristics. There are many ways to connect bolts, and different combinations can be made according to different working stress conditions to form different bolt groups. The bolt set has complete reliability. The bolt set ensures the safety of electrical and mechanical movement. The selection of bolt and bolt group connection form is to determine the distribution form of bolt, the shape of binding surface, the number of bolts and the connection structure form. To determine the appropriate bolt diameter and connection mode, the stress of each bolt is analyzed by the external load (force, torque) on the bolt group. Prevent the bolt from crushing, deformation or even breaking, ensure the reliability of bolt connection. In this paper, the bolt group is analyzed under different stress conditions, mainly including the bolt group connection under transverse load, axial load, torque and overturning torque. At the same time, the influence of bolt preload, friction coefficient, and external load Angle on bolt hole circumference and stress under transverse load is also discussed. At the same time, the finite element analysis of bolt group is carried outAnalysis of bolt group structure and bolt diameter1. Structural analysis of bolt group1. Bolt group connectionThe main purpose of the structural analysis of the bolt group is to analyze the geometrical shape and structure of the joint face of the bolt group connection and to determine the distribution form of the bolt. To this end, emphasis should be given to the following aspects:1) the geometric shapes of the two joint faces of the coupling bolt are usually rectangle, ring, box, circle, triangle, etc.