Analysis and simulation of trajectory planning based on kinematic for UPR100 arc welding robot was carried out. UPR100 arc welding robot kinematics equation was established according to the DH method, and using the Matlab language programming for solving the forward and inverse kinematics equations. The trajectory planning was based on forward and inverse kinematics. Meanwhile a kinematical simulation model was developed by Matlab/SimMechinics, and then comparing the data of theoretical data with the motion data of trajectory planning simulation, the simulation results verify the validity of the simulation model and the rationality of trajectory planning, which provids the basis for the study of the dynamics of the robot and the design of trajectory tracking controller.