The flexibility of the robot arm in combination with the right selection of peripheral equipment allows the welding robot to be widely used in manufacturing industries for complex products, so that simulation is the most important tool to archive high quality and a low cost. The preliminary stage for the development of robot simulation model is first to build the mathematical model and corresponding three dimensional simulation one. This paper represents step by step for development of a simulation model for GMA (Gas Metal Arc) welding process by using CATIA V5 software. Not only the initial simulation model with six degrees of freedom for Faraman AM1 welding robot was developed but also the forward and inverse kinematics equations be obtained by using conventional numerical methods. To verify the correction of the simulation model as well as the correction for kinematics equations of the welding robot, the output data calculated from simulation model was employed in comparison with result data of kinematics equations.