In order to investigate the digestive activity and non-specific immunity activity of GIFT Oreochromis niloticu cultured with biofloc technology(BFT), tilapia[(24.17±2.49)g]were raised in indoor recirculating aquaculture system(control group)and biofloc technology system(treatment group), respectively.During 59 days^, culturing, fluctuations of total ammonia nitrogen(TAN)and nitrite nitrogen(NO₂^--N)in the treatment group were(20.48±14.66)and(33.77±34.57)mg/L respectively, which were significantly higher than those of the control group.Final density(FD)in the treatment was as high as 36.89 kg/m³, individual weight(FIW), weight gain rate(WGR), specific growth rate(SGR)of the treatment group were significantly higher than those of the control group, and the feed conversion rate(FCR)decreased by 18.7%(P<0.05).Nitrogen utilization rate(NUR)of the treatment group was 57.79%, which was significantly higher than the control group(49.51%).Compared with the control group, activities of stomach protease, stomach lipase, intestine protease and intestine lipase of the treatment group were lightly lower, but there were no significant differences.Besides, total superoxide dismutase(T-SOD)activity in hepatopancreas of the treatment group was significantly lower than that of the control group, there were no significant differences of T-SOD, lysozyme(LZM)and alkaline phosphatase(AKP)activities in serum, hepatopancreas and head-kidney between the treatment group and the control group.