In view of the problem that the joint bolt of the gate of the Three Gorge ship lift is broken during the trial operation,we carry out the strength analysis of the bolt under different working conditions under the premise of satisfying the mechanical properties of the gate work gates,apply finite element software of Solidworks Simulation to establish the constitutive model of the bolt and joint plate,simulate the stress field of the bolt and joint plate,obtain the reason of the broken bolt,and propose the optimization scheme of the cylinder hinge.The results show that the original bolt strength preload is less than the maximum working load to cause the broken bolt.The replacement 10.9 grade high-strength bolt can satisfy the actual working conditions,the addition of two ribs ensure the strength of the cylinder hinge bolt connection plate,which can provide the references for the similar projects.