The invention discloses a light metal and silver-base-loaded antibacterial layer and a preparation method thereof. The preparation method is characterized by comprising the following steps: conducting micro-arc oxidization on cleaned light metal, and processing the light metal for 40-70min under room temperature, thus obtaining a micro-arc oxidization ceramic layer with certain thickness; cleaning and drying the metal, pre-processing the metal by sensitization and activation, then putting the metal into blended electroless plating solution for chemical silver plating, processing the metal for30-60min under room temperature, then taking out, cleaning and drying, thus finally obtaining the composite antibacterial layer with a light metal base, a micro-arc oxidation ceramic layer on the surface of the light metal base, and a chemical silver plating layer on the micro-arc oxidation ceramic layer. In the method, the property of the micro-arc oxidation ceramic layer and the process characteristics of chemical silver plating are combined sufficiently, so that the composite antibacterial layer is compatible with the good mechanical performance and high antibacterial performance, and the micro-arc oxidation ceramic layer can be sealed effectively, so that the composite antibacterial layer is compact and uniform.