With the simplified finite element model of optical components established by the software ANSYS, Gaussian heat as heat source model, and the nonlinear transient analysis, the weld temperature field distribution is numerically simulated. The variation laws of welding spot size and depth with laser beam radii and output powers are obtained accurately. The results show that the short-period pulse waveform can effectively improve the welding quality. The depth and width of welding spot increase with the increase of laser output power and decrease with the increase of laser beam radius. And the numerical simulation result is basically consistent with the actual situation, which verifies the applicability of the finite element model of optical components. The study provideds an effective experimental basis for the prediction and improvement of welding quality of optical components in different laser welding processes.