The invention relates to a mesoporous silica-insulin nanometer slowly-released transdermal patch and a preparation method thereof. The mesoporous silica-insulin nanometer slowly-released transdermal patch is characterized in that a medicine loading layer comprises the components of mesoporous silica-insulin nanometer, a pressure-sensitive glue, a penetration enhancer, a crosslinking agent, a bacteriostatic agent, a substrate, a hydrophilic additive and a freeze-drying protective agent. According to the method, the degradable mesoporous silica entraps insulin to prepare a long-acting slowly-released nano blood sugar reducing patch which has the characteristics of being low in side effects, painless and convenient; insulin is the only hormone capable of reducing blood sugar in a body; silicanano microspheres are capable of adsorbing protein type medicines, so that the silica nano microspheres can be used for loading the protein type medicines, and the problem of application and existingof the protein medicine in the human body can be certainly solved; and meanwhile, the silica nano microspheres are high in degradability, and are safe and stable; the insulin can be protected, and the biology enzyme is prevented from damage, and thus the bioavailability is improved; with the adoption of the patch, the purpose of painless and convenient medicine applying in a slow releasing manneris achieved; the preparation method is simple, and convenient; and the production cost is low.