Abstract: The multibody software package ADAMS is used to acquire some important parameters from the CAD model of and HT120 spot-weld robot. Combining proper constraints, forces and movements with the parameters such as geometry, mass distribution and inertia, a virtual prototype machine of the robot is built. A dynamic analysis of the robot is performed. Some key parts like the little arm are treated as flexible bodies and the stress distribution in the little arm is studied using finite element code. The results may be helpful for shape design, structural optimization and fatigue examination.