Abstract: Taken Carassius auratus as experimental material,the accumulation of cadmium in gill tissues of Carassius auratus and its effect on P-glycoprotein(P-gp)activity and gene expression at different Cd exposure concentrations(2.12,4.23 and 8.46 mg/L)in 96 h were studied in this paper. The results showed that the different concentrations and time of Cd had significant effects on the accumulation of Cd,the activity of P-gp and gene expression in the gills of Carassius auratus. After exposed to 2.12 mg/L Cd,the accumulation of Cd reached its maximum at 48 h,and then decreased to a stable level. After exposed to 4.23 and 8.46 mg/L Cd,the accumulation of Cd increased significantly with the prolongation of exposure time,showing a significant time-dependent relationship. After Cd treatment,the activity of P-gp and the expression of mRNA in gill tissues of Carassius auratus increased significantly(P<0.05)and reached the maximum at 72 h under different Cd concentrations. These results suggest that P-gp plays an important role in the mechanism of resistance to Cd in Carassius auratus. It can reflect the concentration or content of Cd in water environment sensitively.