Abstract： This paper reveals that the intensity of the light emitted by aluminum sheet laser welding, which possess a wavelength of 600 nm to 650 nm is nearly constant. A suitable narrow bandwidth filter was selected to prevent the fluctuation of the light, so that the pictures taken by the CCD camera have a coherent intensity. The images taken by two independent CCD cameras driven by pulsing signal simultaneously could reveal the threedimensional deformation, morphology and strain of the entire plate which were welded in the optimal welding parameters in real time. This procedure could help study the sheet laser welding deformation clearly, which was significant in the field of control welding distortion.