Alpha - glucoside inhibitor is used as one of six groups of medicine for treatment diabetes mellitus of type 2. In last decade, Bacillus subtilis has been demonstrated to be able to synthesize a-glucosjde inhibitor under suitable conditions. In this study, fermentation conditions of Bacillus subtilis TH2 to produce aglucoside inhibitors (AGIs) for the diabetes mellitus drug were canied out The results were shown that the best condition for the strain TH2: time of fermentation of 48 hours, substrate concentration of 30 mg/mL, mediwn intial pH: 7 and temperature of 40oC. And the maximun alpha-glucoside inhibitory of 70.5 percent was obtained.