High yield diglycerin borate(DGB) have been synthesized by the raw materials glycerol and boric acid in this paper. The structure of the products was characterized by FTIR and 11B NMR. The yield of the products was discussed by reaction conditions that were material ratio, reaction temperature, reaction pressure etc. and then the optimum process conditions of preparing DGB was decided. In this condition, high yield DGB can be prepared which could reach more than 96%.