The work aims to compare the cavitation erosion resistance of different series of Ni-based alloy sprayed and fused coatings in NaCl solution and explore the coatings’ cavitation mechanism. The sprayed and fused coatings of NiCrBSi, WC-reinforced Ni-based and NiCrBSiCuMo alloy were prepared by oxy-acetylene flame spraying and fusing. The structure, hardness and electrochemical corrosion performance of the coatings in 3.5% NaCl solution were analyzed by XRD, Rockwell hardness tester and electrochemical test system (CorrTest), respectively. Furthermore, resistance of cavitation erosion of the coatings in NaCl solution was studied by ultrasonic vibration cavitation equipment. From the results, NiCrBSiCuMo alloy sprayed and fused coating had excellent corrosion resistance in NaCl solution. It contained not only Cr23C6, Cr7C3, Cr3C2 and Cr2B hardness phases, but also Mo2C and MoSi2 phases which could refine structure and improve toughness of the coating. The coating’s hardness was close to NiCrBSi coating (about 58HRC) and its cumulative volume loss was 65% of NiCrBSi and 51% of WC-reinforced Ni-based alloy coating, respectively. The WC-reinforced Ni-based alloy coating also contained Cr carbide and boride hardness phases in NiCrBSi coating besides WC and W2C hardness phases. Although its hardness was pretty high (59.3HRC), it had relatively low corrosion potential, the highest corrosion current density and the worse erosion resistance in NaCl solution. Thus, NiCrBSiCuMo alloy coating has the best cavitation erosion resistance in NaCl solution and the addition of WC weakens the cavitation erosion resistance of Ni-based alloy coating.