In order to optimize the laser welding process of industrially pure titanium TA2, a nonlinear transient thermal coupling model is established by finite element analysis method on the platform of ABAQUS software in this paper. The thermal stress field during laser welding of TA2 industrial pure titanium with a thickness of 6 mm is analyzed. Considering the temperature dependence of the material thermophysical property parameters, and the combined loading of the moving Gaussian surface heat source and the cone heat source is realized by FORTRAN programming. The reliability of the composite heat source is verified by experiments, and the maximum temperature at different positions in the molten pool and the cooling rates in different temperature ranges under different process parameters are compared and analyzed. The results show that both the laser power and the welding speed have a great influence on the maximum temperature of the molten pool and the cooling rate in different temperature ranges, and the molten pool is more affected by the welding speed.