Abstract: A well-grown once and twice hydroxyapatite coatings on the surface of AZ31 magnesium alloy were produced in 24 and 48 h using a biomimetic technique. The coatings formed on the magnesium alloy were characterized by XRD, and the morphology of sample surfaces was observed by SEM. The samples were subsequently immersed in the simulated body fluid (SBF) for the degradation test. The results indicated that the degradation rate of the two-layer coating samples is slower than the single coating samples, the twice coatings are better than once coating, and it confirms the feasibility to control degradation rate of magnesium alloy by changing the morphology and thickness of coatings.