For evaluating and optimizing the trailing am fatigue performance, taking the trailing arm of a certain vehicle model as the research object, the finite element analysis and the strain signal road data acquisition were carried out. The accuracy of the finite element analysis was verified by comparing finite element analysis results with the test data. The structural optimization of the trailing arm was carried out based on its failure mode. The rapid test multi-level load spectrum was generated based on the road load data, and the rig durability test was carried out for original trailing arm and optimized trailing arm respectively. The rig durability test results were consistent with the finite element simulation and the proving ground durability test.