1. Classification according to the receiving force: pressure-bearing high-strength nuts, friction-type high-strength nuts (1) Friction-type high-strength nuts: Its ultimate bearing capacity is rolling between plates, and the development potential of bolts cannot be fully exerted by friction-type high-strength nuts. (2) Pressure-bearing high-strength nut: its limit condition is the rolling between the plates, and the limit condition of the bearing capacity is the failure of the connection. 2. Maijin is classified according to the engineering construction method: large hexagonal high-strength nuts, torsional shear type high-strength nuts (1) Large hexagonal high-strength nuts: its compressive strength is relatively high compared to ordinary screws. (2) Torsional shear type high-strength nut: In order to use the effect better and faster, it is optimized on the basis of the hexagonal high-strength nut. What high-strength nuts have in common with ordinary bolts is the buckle structure and shape. There are also differences between them. Generally, the transmission of bolt shear stress requires the bending capacity and the bearing capacity of the rod body. When the nut is tightened, the pre-tightening force of the bolt is very small, and its influence is not considered. The high-strength nut connection is deliberately added with a high-torque bolt, so that the contact surface of each part of the connection will generate squeeze pressure. Therefore, there is a very large frictional force to the spiral vertical, and the shearing stress of the connection transfers the frictional force. For high-strength nuts, its pre-tensioning method is to fix the screw cap, and the methods are corner method and torque method. The method of twisting high-strength nuts to control the pre-tightening force is to twist off the tail end of the bolt for operation.