In order to improve the corrosion resistance of magnesium alloys, ZnO-HA coating was prepared on the surface of magnesium alloys by using ultraviolet (UV) irradiation and hydrothermal method. The effects of ultraviolet irradiation time on the microstructure, the electrochemical properties and corrosion resistance of ZnO-HA coating were studied. The results indicated that the ZnO-HA coating obtained by 24 h of UV irradiation combined hydrothermal method was dense and uniform, without any cracks, and it was mainly composed of nanoparticle-like HA and flake-like ZnO. Electrochemical properties and corrosion resistance of ZnO-HA coated magnesium alloys were studied in simulated body fluid (SBF). Compared with the bare magnesium alloys, the coated magnesium alloys have good corrosion resistance. In vitro immersion experiments, ZnO-HA coating could provide good protection for the magnesium alloys substrate, indicating that ZnO-HA coating prepared by UV irradiation combined hydrothermal method can be used as a potential modified biomaterial for magnesium alloys.