Driving axle of a light bus was tested on bench，and the reasons of abnormal vibration and noise were analyzed. 3D model was established by the method of reverse engineering and modal analysis was done by the method of finite element analysis. Finite element model was verified by modal test. Improvement measures were proposed according to oversized impacting of the hypoid gear pair, resonated rear axle housing and resonated rear cover, which were verified through the bench test. The results show that vibration and noise reduced significantly. Those improvement measures were proved practical and effective.