A method for manufacturing a polypeptide-coated biomaterial based on a magnesium alloy AZ31, comprising steps of: ultrasonically cleaning the magnesium alloy AZ31 to remove impurities on the surface of the magnesium alloy AZ31; dissolving polyurethane with chloroform, and then placing the treated magnesium alloy AZ31 into the chloroform solution dissolved with the polyurethane, so that the magnesium alloy AZ31 is fully enclosed in the solution; taking out the magnesium alloy AZ31, and letting the magnesium alloy AZ31 stand until the solution on the surface thereof is solidified; and then activating the polyurethane coated on the surface of the magnesium alloy AZ31 by using a click reaction in a plasma reactor; and finally placing the surface-activated polyurethane-coated magnesium alloy AZ31 into a sodium phosphate solution dissolved with polypeptide and applying vibration to allow them fully react to form the corresponding polypeptide coating; wherein: the magnesium alloy AZ31 is a cold-drawn magnesium alloy AZ31; or the magnesium alloy is provided by the following steps before the ultrasonically cleaning: fully annealing an original cold-drawn magnesium alloy AZ31 in an interference-free atmosphere which eliminates the original processing stress and the texture structure specificity of the original cold-drawn magnesium alloy AZ31, the fully annealing comprises: polishing a surface of the magnesium alloy AZ31 by a waterproof abrasive paper to remove an original oxide layer on the surface while maintaining or improving the finish of the surface; heating the magnesium alloy AZ31 obtained from the step in an interference-free atmosphere created by an inert gas or a vacuum, wherein the magnesium alloy AZ31 is heated to a temperature of 330 °C to 350 °C in the interference-free atmosphere and then the temperature is kept for 3 to 4 hours; letting the magnesium alloy AZ31 obtained from the step complete the fully annealing in the interference-free atmosphere, by cooling the magnesium alloy AZ31 obtained from the step along with a furnace to room temperature, to obtain an equiaxed crystal structure which is texture-even and isotropic. the magnesium alloy AZ31 is a cold-drawn magnesium alloy AZ31; or the magnesium alloy is provided by the following steps before the ultrasonically cleaning: fully annealing an original cold-drawn magnesium alloy AZ31 in an interference-free atmosphere which eliminates the original processing stress and the texture structure specificity of the original cold-drawn magnesium alloy AZ31, the fully annealing comprises: polishing a surface of the magnesium alloy AZ31 by a waterproof abrasive paper to remove an original oxide layer on the surface while maintaining or improving the finish of the surface; heating the magnesium alloy AZ31 obtained from the step in an interference-free atmosphere created by an inert gas or a vacuum, wherein the magnesium alloy AZ31 is heated to a temperature of 330 °C to 350 °C in the interference-free atmosphere and then the temperature is kept for 3 to 4 hours; letting the magnesium alloy AZ31 obtained from the step complete the fully annealing in the interference-free atmosphere, by cooling the magnesium alloy AZ31 obtained from the step along with a furnace to room temperature, to obtain an equiaxed crystal structure which is texture-even and isotropic. polishing a surface of the magnesium alloy AZ31 by a waterproof abrasive paper to remove an original oxide layer on the surface while maintaining or improving the finish of the surface; heating the magnesium alloy AZ31 obtained from the step in an interference-free atmosphere created by an inert gas or a vacuum, wherein the magnesium alloy AZ31 is heated to a temperature of 330 °C to 350 °C in the interference-free atmosphere and then the temperature is kept for 3 to 4 hours; letting the magnesium alloy AZ31 obtained from the step complete the fully annealing in the interference-free atmosphere, by cooling the magnesium alloy AZ31 obtained from the step along with a furnace to room temperature, to obtain an equiaxed crystal structure which is texture-even and isotropic.