Abstract: With the development of artificial intelligence and the robotics industry, various types of maintenance robots have been widely used in the field of urban rail transit. The structural design of subway maintenance robots has also evolved from static and rigid design to dynamic and flexible design. This paper selects a certain model of subway maintenance robot vertical arm pull rod as the research object, establishes a multi-body dynamic model of the whole machine in ADAMS, and applies the trajectory inverse method to obtain the driving curve of the driving joints. And the paper uses ANSYS software to generate a flexible body of a vertical arm pull rod, and after replacing the rigid body, conducts dynamic simulation of rigid flexible coupling. The generated load file is used as the load input for transient dynamic analysis of the boom rod, which enables the estimation of the strength of the main structure in the design stage and is of great significance for the study of component fatigue life. This article can achieve the estimation of the strength of the main structure during the design phase.