In order to study the influence of laser power on laser quenching of 27SiMn steel for hydraulic support post, ANSYS finite element software was used to simulate the process of laser quenching, and the temperature field distribution under different power was obtained. The laser quenching experiment on 27SiMn steel was carried out under the same conditions as the numerical simulation, and the macrostructure, microstructure and microhardness were analyzed. The results show that the depth of quenching zone obtained by numerical simulation and experiment is basically the same. In the numerical simulation, the peak temperature of the workpiece increases with the increase of the laser power, and the cross section of the whole temperature field is semilunar. The morphology of the hardened layer obtained by the experiment is similar to the simulation result and is semilunar. After quenching, fine and dense martensite microstructure is formed on the surface of the matrix, and the hardness of the hardened layer is increased by more than 2.5 times than that of the matrix, and the depth and hardness of the hardened layer gradually increased with the increase of laser power.