The invention discloses a stretch repair process of a hydraulic cylinder piston rod, and relates to the technical field of hydraulic equipment, which solves the problems of bad repair effect and environmental pollution of an existing electroplating repair process of the hydraulic cylinder piston rod. The stretch repair process comprises the following steps of (1) completely turning an original electroplated layer from the surface of a piston rod by using a lathe, and determining the turning depth according to the thickness of the original electroplated layer; (2) cleaning the surface of a damage with trichloroethylene or perchloroethylene; (3) performing sand blasting treatment on the surface of the damage of the piston rod; (4) sending metal alloy powder to the surface of the damage of the piston rod; (5) irradiating the surface of the damage of the piston rod with laser, so that the metal alloy powder is molten so as to form a repair layer; (6) insulating the repaired piston rod, andslowly cooling to room temperature; and (7) further processing the surface dimension and roughness of the piston rod by using turning and polishing equipment. The repair process has the advantages ofhigh strength of the repair layer, long service life and no pollution.