Based on the brightness value distribution of a range of shaped Gaussian laser beams measured by a CCD camera, an analytical model presenting the laser power density field has been established by using Gaussian distribution function considering the divergence characteristics of laser beams. A simulation of a sheet metal laser scanning process has been conducted by embedding the analytical model into FE software ABAQUS and compared with a corresponding experiment. The results reveal that the simulated temperature field agrees well with the measured one by an error within 7%, indicating the good accuracy of the analytical model and enhanced the foundation of the application of thermal laser scanning.