Magnesium (Mg) is a promising biomedical material due to its suitable mechanical properties and biocompatibility. The rapid dissolution in the physiological environment limits its application. There has been growing attention to pure Mg with different microstructures and coated Mg by chemical bath deposition method for bone tissue clinical use. However, the influences of microstructure on mechanical property and corrosion resistance of Mg and the relationships among the substrate, bath temperature, and coating quality are undetermined. This research achieved the pure Mg sheet by rolling and post-heat treatment. The in-situ coating was produced in a chemical solution containing Ca2+ and HPO42- under different temperatures of 37 °C-100 °C. The polarization and 30-day immersion tests were carried out to study the anti-corrosion performance of bare and coated Mg. The Mg mechanical property and the coating formation mechanism were discussed. According to the test results, it was concluded that the grain boundaries played a dual role in the mechanical property and corrosion behavior. Because they worked as physical barriers to improve strength and corrosion resistance, they also acted as crystallographic defects resulting in the adverse function when the crystalline size was super fine. The corrosion products were primarily Mg(OH)2. Calcium/magnesium phosphates and carbonates were deposited as thin outer precipitates. For the coated Mg, although improving the applied temperature offered more energy for the nucleation and growth of the precipitations, the substrate dissolution was accelerated. The coated Mg obtained at 70 ℃ on the substrate rolled at 200 ℃ had the best anti-corrosion behavior. The coating was in a double-layer structure. The inner layer was Mg(OH)2, and the outer one contained good-crystallized CaHPO4.2H2O and a small amount of Ca10(PO4)6(OH)2 and MgO. Due to plenty of Ca and P from the coating dissolution, the newly formed corrosion products had the same element content as the outer layer of the coating. They could retard the further erosion of the inner substrate. Because of this self-healing effect, the substrate was protected during the whole immersion process. This dissertation provides a combined strategy of substrate preparation and coating deposition to develop Mg-based materials for practical applications
