The invention discloses a method for preparing dihydrophenylglycine methyl ester methyl hydrosulfate, belongs to the technical field of chemical synthesis, and is characterized in that the method comprises the steps: adding dihydrophenlglycine and methanol into a reactor provided with a rectification water separation device, adding excess concentrated sulfuric acid with the mol ratio of dihydrophenlglycine to concentrated sulfuric acid being 1:1-1:2, then carrying out heating reflux, carrying out an esterification reaction, adding an azeotropic water-carrying agent dichloromethane, uninterruptedly separating water generated from the esterification reaction and brought by a dichloromethane and water azeotrope, carrying out reflux water carrying for a period of time, and basically completing the dihydrophenlglycine esterification reaction. The method has the advantages of simple operation, short time of working procedures, high product yield and the like.