Abstract: The monitor technique of the deformation of 5052 aluminum alloy sheet during laser beam welding was achieved in the paper. In welding process, the selected particular point's dislocation was captured with accuracy to obtain the deformation over time. Compared with the traditional method, digital image correlation technique possess the superiority of non-contact detection and highly accuracy. Finally, deformation of aluminum alloy sheet under different laser beam welding parameters was obtained and displayed in three-dimensional cloud. The results shows that the deformation increases as the welding power increasing, decreases as the welding speed increasing, and decreases as the defocusing amount increasing.