Pure magnesium has become a barrier to surgical transplant materials for its rapid corrosion rate. In order to control its degradation rate, this study presents a two-step procedure to prepare composite coating by BTSE(1,2-Bis(triethoxysilyl)ethane) silane treatment and covalent bond grafting crosslinking modification sodium hyaluronate via EDC-NHS. At the same time, the physical and chemical properties of the coating are analyzed by infrared spectrum (FTIR), X ray photoelectron spectroscopy(XPS), atomic force microscope (AFM) and static contact angle method (CA),the corrosion resistance of the coating in simulated body fluid is analyzed by electrochemical behavior. The results of FTIR and XPS show that the composite coating is successfully prepared on the surface of pure magnesium. Other results reveal that the surface of the cross-linked sodium hyaluronate coating is more smooth than that of bare magnesium and silane, also taked on hydrophilicity to improve its biological activity. Compared with the unmodified pure magnesium, the corrosion current density of the composite coating is reduced by two orders of magnitude, the impedance value is increased by three orders of magnitude, demonstrating better corrosion resistance of the composite coating. The results show that the composite coating as surgical transplant material has great prospect in medicine.