In order to study the effects of fermented soybean meal replacing of fish meal on the growth, feed utilization, apparent digestibility and digestive enzyme activity of largemouth bass (Micropterus salmoides), we employed soybean meal with aerobic fermentation by Bacillus subtilis as a partial substitute for fish meal with equal nitrogen and equal energy. 0% (FM group), 10% (FSM10 group), 15% (FSM20 group), 20% (FSM30 group) and 25% (FSM40 group) of fermented soybean were respectively used for replacing 0%, 10%, 20%, 30% and 40% fish meal. Largemouth bass, initial weight, (19.83±0.33)g were randomly divided into 5 groups, each group had 3 replicates and every replicate contained 30 fish. The largemouth bass were fed twice a day (7:00 and 17:00) for 75 days. The results showed that: there were no significant differences in the feed coefficients of five groups (P>0.05), however, the final average weight and specific growth rate of FSM20 and FSM30 groups were significantly higher than those of other groups (P<0.05); proteins efficiency of each group showed no significant differences (P>0.05), the food intake of FSM groups were significantly higher than that of the FM groups (P<0.05), and the protein deposition rate and fat deposition rate of the FSM40 group were significantly lower than those of the other groups (P<0.05); there were no significant differences in whole fish crude protein in each group, and the maximum value appeared in FSM20 group (P<0.05), and crude fat of whole fish in FSM groups was significantly lower than that in FM groups (P<0.05); there were no significant differences in protein digestibility and fat digestibility between all the groups (P>0.05),and apparent digestibility of dry matter of FSM30 and FSM40 were significantly lower than that of other groups (P<0.05); there were no significant differences in the activities of protease, amylase and lipase between the FSM groups and the FM groups while fermented soybean meal was less than 15%.