The invention discloses a magnesium alloy surface modification method which comprises the following steps: pretreating the magnesium alloy surface, performing micro-arc oxidation, and forming a micro-arc oxidation coating; depositing poly-dopamine on the micro-arc oxidation coating, immersing the magnesium alloy on which poly-dopamine is deposited in a hydroxyapatite solution, thereby obtaining a surface modified magnesium alloy. The micro-arc oxidation can provide a corrosion prevention effect for the magnesium alloy, the hydroxyapatite belongs to bioactive degradable ceramics and is deposited on the surface of the micro-arc oxidation magnesium alloy, the biological activity can be effectively improved, and adhesion and growth of osteoblasts on the material surface are promoted, so that the requirement on the magnesium alloy serving as an in-vivo implant material is met. Compared with the conventional electrodeposition method for preparing a hydroxyapatite coating, the method disclosed by the invention has the advantages that instruments and equipment are not needed, the cost is low, and the application range is widened.
