The invention relates to a polylactic-acid-modified
magnesium alloy medical
composite material and a preparation method thereof. The method comprises: 1) performing
micro arc oxidation treatment on a surface of a
magnesium alloy substrate, and performing
coupling treatment to obtain a silicane
coupling substrate; 2) adding a surfactant to a
chitosan solution, and performing uniform mixing to obtain a
chitosan mixed liquid, and dissolving
polylactic acid in trichloromethane to prepare a
polylactic acid solution, and adding the
polylactic acid solution in the
chitosan mixed liquid while performing stirring, and performing high speed emulsification to obtain a film-
casting liquid; and 3)
coating the surface of the silicane
coupling substrate with the film-
casting liquid, removing the
solvent and the surfactant to obtain a dry film layer, and performing
thermal insulation at 80-90 DEG C to obtain the
composite material. The
composite material is excellent in biological compatibility, surface activity and mechanical properties. The degradation rate of the material can be controlled by adjusting the thickness of a polylactic acid and chitosan film layer. After the material is implanted to a
human body, the degradation product can be absorbed by the
human body or excreted outside the body with
metabolism, so that secondary operation is not required.