Overuse of antibiotics, such as erythromycin through different ways go into the water, then into the sediment, causing harm to aquatic ecosystems. The benthic animal Cipangopaludina chinensis exposed to roxithromycin, were detected the ERND in the stomach, liver, kidney and ovary, examining the impact of roxithromycin on the activity of ERND enzyme in C. chinensis. The results showed that with the P450 isoform of cytochrome P450 activity, but they are in the distribution and activity of tissues and organs does not show difference in C. chinensis. Continuous administration to the C. chinensis,The ERND activity in liver, kidney, stomach, ovary and muscle tissue increased obviously, the dose effect relationship to reach the highest point in 3 days, and began to decline in 4 days. The overall trend is promoting more than restraining, but the inhibitory effects of different concentrations of roxithromycin have not great difference. From the point of view of the survival status of the control group and the experimental group of each snail, roxithromycin as an antibiotic, has no lethal effect on C. chinensis, but 250 times the concentration used in this experiment, 500 times and 750 times the concentration of environment can produce concentration has obvious influence on the ERND activity in tissues of C. chinensis.