Abstract: Aiming at the fragmentation problem of a certain type of rail transit vehicle grab handle, the after-sales follow-up investigation of the grab handle fragmentation of the maintained vehicle discovers that a large number of grab handle breaks within the warranty period, and the cracks basically occur in the same area. It can be primarily judged that grab handle breaks because of the design flaw. Through research and analysis of grab handle strength and manufacturing process, it is found that there are multiple factors leading to the fragmentation including unreasonable structure, inadequate processing technology and insufficient control of assembly tightening torque. According to the analysis results, an optimization scheme for product structure and manufacture process is proposed, and optimized samples are tested. Test results show that the fragmentation problem of optimized grab handle is significantly improved.