In view of the problem of gear root bending strength with the large modulus rack and pinion meshing under the condition of tooth surface wear,the simulation test bench of the vertical rack and pinion lifting mechanism was built with the gear rack and pinion transmission pair of the Three Gorges ship lift as the research object,and the changes of related parameters such as the load along the tooth profile and the gear tooth thickness after wear were studied by the gear displacement method.The gear root bending stresses of normal,1/12 wear,1/6 wear and 1/4 wear were analytically calculated and experimentally verified.The results show that the gear bending stress increases with the increase of wear and load,the bending stress in the single-tooth meshing interval is significantly higher than that in the double-tooth meshing section,and the proportion of single-tooth meshing time increases with the increase of wear,indicating that gear wear deteriorates the working conditions of the transmission system and accelerates the performance degradation process of the transmission system.Through the quantitative analysis of the meshing bending stress of single and double tooth segments,the maximum error value of analytical calculation and experimental verification is 4.02%,and its value is at a low level,and the results of the two methods verify each other,the correctness and accuracy of the analysis are guaranteed.