AlCoCrxFeCu (x: molar ratio, x =1.0, 1.5 and 2) high-entropy alloy coatings was synthesized on 304 stainless steel with premixed high-purity Al ,Co, Cr and Cu four-component powders by laser cladding. The Fe component is obtained from melting substrate metal during laser cladding. The effect of Cr content on their phase evolution, microstructure, microhardness and cavitation erosion behavior of high-entropy alloy coatings was investigated using XRD, SEM, EDS, and ultrasonic cavitation erosion testing machine respectively. Results showed that AlCoCrxFeCu coatings was composed of BCC and FCC solid solution. The microstructure of the coatings exhibited a typical dendritic structure of high entropy alloy. The microhardness of AlCoCrxFeCu coatings increased obviously to 570 HV, which was at least 2.3 times that of substrate metal (250 HV). AlCoCrxFeCu high-entropy alloy coatings lost 9.4 mg in 10-hour ultrasonic cavitation test in distilled water, far less than 403 martensitic stainless steel.