The service environment and operating conditions of the large modulus pinion and rack driven hoisting mechanism are complex,and the coupling between the system components is increasing day by day.In the alternating operation cycle of multi tooth-single tooth-multi tooth,the load-bearing stress of single tooth meshing is higher than that of multi tooth meshing.Therefore,it is necessary to analyze the changes of strength and stiffness of single tooth meshing in order to improve the accuracy of the research about the bearing capacity of pinion and rack pairs.Taking the Three Gorges ship lift as the research object,the working condition simulation test bench of vertical pinion and rack hoisting mechanism was built,six kinds of working condition were studied,and the contact strength and bending strength of pinion and rack hoisting mechanism were theoretically analyzed.Two kinds of stress and stiffness changes of single tooth during working period were simulated and analyzed by finite element software,and it was compared with theoretical analysis.The accuracy of the theory and simulation was verified by experiments,and the errors were all about 10%.The simulation results show that the meshing stiffness of the single tooth increases with the increasing angle and load,and the changing trend of the strength is consistent with it.