In order to study the effect of laser power on the microstructure and properties of laser cladding 304 stainless steel, the process of laser cladding 304 stainless steel at different laser power was simulated by using ANSYS software. The temperature field under different laser powers was analyzed, and a temperature-time curve at a point 1 mm from the surface of the cladding layer was obtained. A single laser cladding 304 stainless steel experiment was carried out on the surface of 27SiMn steel, and the microstructure, macroscopic morphology and microhardness were analyzed. The results show that the width, depth and area of the temperature field by numerical simulation increase with the increase of laser power. The temperature time cure of this point changes in a sawtooth shape, and the maximum temperature increases with the increase of laser power. Under different laser power, good metallurgical bonding is achieved between the cladding layer and the substrate. The laser power is in the range of 2 100 W to 2 500 W. With the increase of laser power, the grains of the cladding layer become finer and the structure is more compact. When the laser power is 2 700 W, the cladding grain is larger than the power of 2 500 W. The microhardness curves show a step-shaped distribution trend of "low-high-low".