In this paper, the three-dimensional measurement system of laser composite forming is designed, and the dimensional accuracy control of forming parts is studied. The function of the three-dimensional measurement system and its role in laser composite forming technology are analyzed. The mechanical structure part of the 3D measurement system is designed, including two-dimensional motion platform and high-speed profilometer bracket. The designed 3D measurement system can measure the surface topography characteristics and surface data of cladding parts; through matlab processing, the milling frequency is 30.05 Hz, the milling speed is 3.02 mm/s, the power is 102 W, the pulse width is 1.05 ms, and the defocusing amount is 0 mm. The convex points and high points of the cladding parts are processed by the data visualization software, and the images of the cladding parts with the same size and can be used by the laser milling software are obtained File. According to the processing pictures, the laser equipment can effectively mill the high and convex areas with an accuracy of 5.01 μ m, which can reduce the slag on the surface and side of the cladding parts, complete the three-dimensional accurate milling of the cladding parts, and realize the closed-loop control of the three-dimensional morphology.