The invention relates to the technical field of cavitation-erosion-resistant coatings, and discloses a method for preparing a cavitation-erosion-resistant coating through a thermal spraying and laserre-melting compound technology. The method comprises the following steps that (1) a metal ceramic composite coating is prepared on a matrix through thermal spraying; and (2), laser re-melting treatment is carried out on the metal ceramic composite coating obtained in the step (1), the surface of the metal ceramic coating is re-melted to form a new structure under high-density energy of lasers, thestructure property of the coating is enhanced after cooling, and the cavitation erosion resistance of the coating can be greatly improved. The method effectively eliminates the problem that ceramic powder deposits on the surface of the matrix through direct laser cladding, the obtained coating is low in porosity, the surface is compact and smooth, the cavitation erosion resistance is excellent, the coating can be widely applied to propellers, water turbine blades and other equipment prone to cavitation damage, the service life of the equipment can be prolonged, the frequency of maintaining the equipment due to cavitation damage is greatly reduced, and the using efficiency of the equipment is improved.