Abstract. In the applied process of robot off-line programming technology, it is necessary for the model to solve the correction problem which is between the practical working and off-line simulational environment. Robot coordinate system calibration method is proposed by measuring workpiece coordinate system and base coordinate system, homogeneous transformation matrix of coordinate measuring system. The kinematics analysis for FS30L robot is done and off-line programming system for welding robot is developed in VC ++. The modularization design is applied in the system. It includes the modules of coordinate system calibration, off-line programming, off-line simulation, serial communication, function extension. By the example verification for the system, the experiment results show that the offline programming system is rational and feasible.