The composite Ni-Cr-Mo covering layers with excellent corrosion and wear resistance are deposited by plasma transferred arc (PTA), which can improve the service life of ships and solve the corrosion and wear problems of mechanized boats. The effects of Mo on the microstructure, hardness and corrosion resistance of covering layers were analyzed by OM, SEM, XRD, EDS, a micro hardness test, a friction test and a corrosion-resistance test. The results show that the structure of covering layers change and the austenite precipitates become granular with an increase of Mo content. In addition, the corrosion and wear resistance of covering layers are improved and the sample with 5% content of Mo has the best wear and corrosion resistance.