Abstract: A real-time imaging system has been established with charge coupled device camera and hybrid filtering technology.With spectral analysis system,the arc light spectral distribution in pulsed gas metal arc welding(P-GMAW) has been measured,and two filtering spectral windows suitable for the imaging of weld pool in P-GMAW have been proposed.The quality of pool images,taken with two kinds of filtering systems in which the middle wavelengths are 665 nm and 1 064 nm respectively,has been compared.A sequence of pool images in a single pulse have been taken and the results indicate that the end of base current period is the optimal imaging time.With the filtering system,whose middle wavelength is 665 nm,very clear weld pool images in base current period have been captured by imaging from up-rear direction of weld pool.Meanwhile,the imaging mechanism has been analyzed.A series of image processing programs have been developed,and accurate pool profile has been extracted.