Abstract: In order to obtain a low-cost and high-performance transmission shaft, the transmission shaft of passenger car was used as the research object to design the transmission shaft structure, and the material and structure were modified according to the results of the finite element analysis. The transmission shaft model was established by using Catia software. The mechanical properties, the vibration characteristics of the transmission shaft under the maximum torsional load were simulated and analyzed on ANSYS Workbench, and the vibration mode, the stress and strain distribution of the transmission shaft under this working and constraint condition were obtained. The results indicate that the torsional stiffness of the transmission shaft follows the design requirements. At the same time, the vibration frequency of the transmission shaft under constraint condition is higher than that of the maximum engine speed, so the transmission shaft would not resonate with the engine. However, the maximum stress in the cross shaft of transmission shaft is higher than its yield strength after assembling. The flange fork, the universal joint fork and the spline shaft are not meet the design requirements because the minimum safety factor should be higher than 1.5. Based on these results, the material and structure of flange fork, universal joint fork, cross shaft and spline shaft are modified. It was found that the safety factor of each part in the modified transmission shaft assembly was higher than 1.5, which met the design requirements. The torsional stiffness of the shaft and the minimum value of the vibration frequency were increased, further improving the safety of the drive shaft.