The invention discloses a piston top surface thermal fatigue-resistance alloy coating laser cladding method. The method comprises the following steps: the top surface of a piston blank is mechanically pretreated; a laser walking trajectory is set according to the piston top surface structure; Co-Cr-W alloy powder is used as a cladding material, and is synchronously added to the piston top surface during laser walking; the laser cladding is performed for the piston top surface; and a thermal fatigue-resistance alloy coating layer formed on the piston top surface is a cladding layer. The piston top surface thermal fatigue-resistance alloy coating laser cladding method selects the proper cladding material to embed the laser cladding technology in the piston manufacturing process flow; the thermal fatigue-resistance alloy coating layer metallurgically bonded with a matrix, with controllable thickness and without crack defect is prepared on the piston top surface; and the piston service life is prominently prolonged.