Abstract: The D-H parameters of an ER series towed welding robot were determined by MDH (modified Denavit-Hartenberg) method, and the corresponding joint coordinate system and DH model were created. The kinematics analysis is solved based on Tool-box 10.4 in Matlab software. The linear multiplication of the homogeneous transformation matrix is used to deduce the forward solution of the kinematics, and the closed solution of the inverse kinematics equation is solved by Newton-Raphson method, which verifies the rationality of the kinematics modeling of the robot. The trajectory planning is completed in Matlab, and the motion trajectory is programmed with cubic and quintic interpolation methods in joint space respectively. The work space analysis of the robot arm under global and limited conditions is completed, and the overall simulation results fully prove that the motion performance of the towed welding robot is reasonable and stable. This scheme lays a theoretical foundation for further experiments and research and development, and has practical application significance for the same series or configuration of robotic arms.