In this paper,the plate welding experiment of 304 stainless steel was carried out by using laser self-fusion welding technology,and the test results were analyzed from the microstructure and mechanical properties. Optimum process parameters as follow,laser power 2.6 kW,welding speed 1.8 m/min,defocus amount +2 mm. The composition of austenite and ferrite in welded joint was obtained by metallographic structure characterization,X-ray fluorescence diffraction and electron back scattering diffraction. According to the best process parameters,the large-scale general finite element simulation software ABAQUS is selected,and the combined heat source of Gaussian surface heat source and Gaussian rotating body is used to simulate the laser welding process. The cross-sectional morphology of the weld obtained by simulation and the cross-sectional morphology of the weld obtained by the experiment are compared,and the simulation model is optimized according to the comparison result. The simulation results show that in the front of the moving heat source,the concentration of isotherms is large,and the temperature gradient is large,while behind the moving heat source,the isotherms are sparse and the temperature gradient is also reduced.