Abstract: According to the weld pool sensing in GMAW of short-circuiting transfer, an ordinary industrial CCD camera was applied and a specially-made composite filter lens was chosen with analysis of the arc spectrum.A proper sampling time was selected. A short-circuit detection and CCD camera ex-trigger circuit were developed based on the welding voltage waveform.The exposure time of the CCD camera was fixed at the moment of short circuit.The experimental results show that grabbed from the front position with small angle and the rear position with large angle, uninterrupted, clear and undistorted images of weld pool are obtained by the ordinary industrial CCD camera.A series of image processing algorithms were also developed to extract the weld pool edge, which is proved effectively in detecting the real and entire edge.