Abstract: The key to the surface height calculation of pulse GTAW welding pool based on shape from shading (SFS) is to build up a surface model of welding pool. Based on the imaging characteristics of aluminum alloy pulse GTAW welding pool, the surface reflectance model is built after analyzing arc intensity, filter system, welding pool shape and reflectance characteristics. With smooth constraint condition of the welding pool surface and variable factor successive over relaxation(SOR) method, the height of welding pool surface is calculated and the error is analyzed.