Soybean meal was inoculated with Bacillus subtilis J3 and Lactobacillus plantarum JNX. The soybean peptides were prepared through solid-state fermentation with one-variable-at-a-time strategy,using the contents of small peptides and volatile basic nitrogen as parameters. The soybean peptides were characterized. The highest content of small peptide reached 10. 64% and the lowest content of volatile basic nitrogen was 50. 70 mg /100 g under the optimized conditions as follows: the ratio of L. plantarum JNX to B. subtilis J3 was 2∶ 1,the ratio of material to water was 1∶ 0. 6,inoculum concentration was 6%,soybean meal was fermented at 30℃ for 24 h. The results of SDS-PAGE showed that soybean meal was degraded to small peptides with molecular weight below 10 k Da and the antioxidant activity of soybean peptides reached 65. 76% after soybean meal was fermented at 30℃ for 48 h. The analysis of amino acid components showed that the content of essential amino acid including Methionine,Leucine,Valine,Isoleucine,Phenylalanine etc. was 5 times higher in the fermented products than that in the un-fermented products.