Abstract: This paper presents a research on dynamic simulation of an experimental robot,type 5R,with a typicalstructure,usually used for continuous path are-welding.The simulation results of the first three joints areobtained when its hand moves along a straight line,2 meters long,within 50 seconds for are-welding movement,and 2 seconds for point-to-point movement.Based on the analysis of the simulation results with some comparison,this paper makes quantitative investigation on the relation of dynamic moments.Finally,the robot performance is evaluated,and measures are taken to improve its structure design.