Abstract: To enhance the understanding and control of arcexcited ultrasonic, factors that influence the arc-excited ultrasonic intensity were studied.Firstly, a welding information acquisition system was built to track the signal variations during the welding process, and it was effective to record the signal.Secondly, the variations of the arc-excited ultrasonic intensity in the air and the workpiece were measured under different parameters, and it was concluded that exciting power is the main factor to influence the excited ultrasonic intensity, and the relation curve was given, which provided useful experiment data for the mechanism study of arc-excited ultrasonic to improve the quality of welded joint.