Abstract: An optimization of parameters in fermentation process of soybean protein by cooperation of Bacillus Subtitles 1398 and Alcalase for peptides were studied and antioxidant activities of primitive peptides were determined.With the soybean peptides content as index, through single-factor and orthogonally experiment of additive amount of enzyme and water, inoculum size, fermentation temperature and fermentation time, the optimal fermentation methods were obtained under the condition of synergy fermentation of bacteria and Alcalase. The optimal condition was as follows: 240U/g of Alcalase, 2.0% of inoculum size, 165% of water, 44℃ of fermentation temperature, and 36h of fermentation time. Under the optimized fermentation condition, the peptides content reached ( 336.8 ± 24.2) mg /g.The inhibition rate to DPPH· and O-2 ·of fermented peptides increased 106.92% and 38.63% to the self-made enzymatic peptides, respectively. The result indicated that mixed bacteria and enzyme synergy fermentation was helpful for improving peptides content and antioxidant activity of soybean protein meal.