The invention discloses a preparation method of arginine glucoside, which comprises the following steps: adding arginine and maltose into glacial acetic acid, adding a maillard reaction inhibitor, reacting for 10 min to 2 hours to obtain a total reactant; concentrating the total reactant under a low-temperature and vacuum condition to obtain an extract, stirring the extract with silica gel by a dry process, evaporating acetic acid, applying the extract to a 200-300-mesh silica gel column, eluting the column with 50-90% ethanol, collecting each flowing component, detecting the components by thin-layer chromatography, collecting a portion of the eluate with a Rf value of 0.2, concentrating the eluate under a low pressure, freeze-drying the eluate into powder, dissolving the powder in an aqueous acetic acid solution, applying the solution to a polyacrylamide column, eluting the column with the aqueous acetic acid solution, collecting each flowing component, detecting the components by thin-layer chromatography, collecting an eluate with a Rf value of 0.2, concentrating the eluate under a reduced pressure, and freeze-drying to obtain a product. The preparation method of the invention can increase the AFG conversion rate in the synthesis, reduce the generation of reaction by-products, decrease the generation of melanoid which is an end product of the maillard reaction, and thus greatly reduce the cost of the separation and the purification of AFG; the invention provides an medical effect of AFG on the prevention and the treatment of type 1 diabetes and type 2 diabetes.