Abstract: A Mo/high-carbon steel composite coating on the substrate of aluminum alloy LY12 is sprayed on by wire explosion spraying. When the composite coating is sprayed, Mo is sprayed firstly. And then, high-carbon steel (0.8%C) and Mo are sprayed alternately. After the composite coating is sprayed, the surface of the composite coating is inspected. The binding strength between the coating and the substrate, the hardness and the thermal-shock resistance of the coating are also tested. These tests show that the density, binding strength and hardness of the coating are high and the thermal-shock resistance of the coating is good.