Based on the DenavitHartenberg (DH) method, the kinematic model of Saddleshape weld robot is built in the basis of joint variables. The forward kinematics and inverse kinematics of saddle welding robot were analyzed. Trajectory planning of weld robot was based on the cubic polynomial interpolation method, using the MATLAB Robotics Toolbox to simulate the Saddle welding robot kinematics, the track figure of the welding gun terminal execution mechanism and the relation curves that angular displacement, angular velocity and angular acceleration vary with time were obtained. The rationality of the designed parameters is verified, and achieved good effect.