The invention provides a metal-ceramic composite coating layer for a steel piston. A mature arc spraying technology is introduced; a layer of such compact materials easy to perform electrochemical oxidation as aluminum, magnesium and titanium is firstly prepared on the top surface of the steel piston; and then, on this basis, such electrochemical methods as hard anodic oxidation and microarc oxidation are used for preparing a thermal insulation layer. An area to be treated of the steel piston is machined; the arc spraying is adopted to form a metal transition layer on the surface of the machined steel piston; the steel piston covered with the metal transition layer is secondarily machined; and a ceramic thermal insulation layer is prepared on the surface of the secondarily machined steel piston by adopting the electrochemical method. As the metal spraying difficulty is far lower than the spraying of such ceramic materials as zirconium oxide and aluminum oxide, the arc spraying is particularly adopted, and the manufacturing cost is greatly reduced.