Abstract: Aimed at the positioning of the welding torch in the welding simulator, one new positioning system was designed. In this system, the coil film was put on the welding plate, so that the welding torch's X and Y coordinates projections in the welding plate could be got. The Z coordinate could be captured by optical fiber sensor indirectly, and the posture of welding torch was captured by a 3-axis gyro and a 3-axis accelerometer, and then the weld pool's position and the trainee's action could be gained according to the geometric relationship. The results shows that, this kind of design could meet the requirement of welding simulator's real-time and accuracy.