The present invention discloses a method for preparing lower graft degree GSGs, and belongs to the technical field of biosynthesis of sweeteners. The method uses amylase to catalyze hydrolysis of GSGs with a high graft degree, thereby obtaining GSGs with low graft degree mainly containing GSGs with a low grafting number. The content of mono- and di-glucosyl substituents in the SGs in the product was 60% or more of the total glycosides, and the mass percent of the GSGs with a glucosyl grafting number of 3 or less was higher than 70% of the total glycosides. The mono- and di-substituted GSGs obtained by enzyme catalysis by the present invention were structurally similar to those, belong to a mixture of the isomers thereof, and have good sweetness and a flavoring function.
