To analyze the influence of defects of rack on the operation of the Three Gorges ship lift during its trial navigation，a three-dimensional finite element model of rack-gear contact with inclusions and pits was established by using Ansys Workbench finite element analysis software.The influence of different defects on rack-gear operation was analyzed by analytical solution and nonlinear finite element calculation.The results show that the inclusion and the pit in rack have different effects on the force of rack.The method provides a scientific theoretical basis for the inclusion content control in rack and rack-gear operation and maintenance.