Objective: To optimize the anodized film on the magnesium surface and explore its effect on the structure,corrosion resistance and biocompatibility through anodizing and annealing treatments.Methods: Pure magnesium was anodized with different voltage parameters (5V, 10V, 20V, 40V), and then annealed at high temperature. The surface and cross-section morphology of the coatings formed were analyzed by scanning electron microscopy.Three-dimensional structure and roughness were analyzed by atomic force microscope. The corrosion behavior of each group of samples was evaluated by electrochemical polarization experiments and in vitro immersion test.The proliferation activity of mouse osteoblasts MC3T3-E1 was evaluated by the CCK-8 method. Results: The increase of the voltage can make the surface coating become porous from the lamellar shape, and then continue to increase voltage，the layer become smooth and uniform. The annealing treatment maintained the basic morphological characteristics, the coating thickness increased and the roughness decreased.The corrosion resistance of the unannealed coating does not increase due to the existence of micropores and the instability of magnesium hydroxide. The dense magnesium oxide crystalline coating formed by the annealing has a certain protective effect. The 40V post-oxidation annealing group has relatively good corrosion resistance and has no obvious inhibitory effect on cell proliferation.Conclusion: Voltage affects the structure of anodized coating. Annealing can further stabilize the coating and improve its corrosion resistance.The 40V post-oxidation annealing group has a better corrosion resistance and biocompatibility .