Multi-degree of freedom manipulators have become a hotspot in the field of robotics because of many advantages. In this paper, a 5-DOF manipulator was taken as the object of study. The modal analysis on it was carried out by methods of test and finite element analysis. A model updating method based on sensitivity analysis was put forward, and the final finite element model was established by iterative optimization. By means of correlation analysis and MAC modal judgment criterion, it was verified that the simulation results of the final simulation model of the manipulator have a good correlation with the experimental modal results. The finite element model determined by this method accurately reflected the actual structural dynamic characteristics of the manipulator.