Two kinds of hydrophobic coatings on ZE41A magnesium alloy are successfully synthesized using hydrothermal method. The surface morphologies, wettability and anti-corrosion properties of hydrophobic coatings are investigated by the method of scanning electron microscopy, X-ray diffraction and electrochemical corrosion tests. Results show that the sample treated in stearic acid ethanol solution with addition of NiSO4 exhibits a morphology possessing large numbers of fine flower-like micro/nano structures, which results in better hydrophobicity and better corrosion resistance.