The application research of laser in heat treatment began in the early 1970s, and then entered the production application stage from the laboratory research stage. When the focused laser with high energy density (10W/cm) irradiates the metal surface, the metal surface rises to the quenching temperature within a few hundredths of a second or even a few thousandths of a second. Because the temperature of the irradiation point rises very quickly, the heat cannot be conducted to the surrounding metal, so when the laser irradiation stops, the metal around the irradiation point will be used as a quenching medium to absorb a lot of heat, so that the irradiation point will be cooled quickly, and a very fine structure will be obtained with high mechanical properties. If the heating temperature is high enough to melt the metal surface, a smooth surface can be obtained after cooling. This operation is called glazing. Laser heating can also be used for local alloying treatment, that is, a layer of wear-resistant or heat-resistant metal is coated on the parts of the workpiece that are easy to wear or need heat resistance, or a coating containing wear-resistant or heat-resistant metal is coated, and then it is quickly melted by laser irradiation to form a wear-resistant or heat-resistant alloy layer.