We constructed 3 types of agricultural drains in The Taihu Lake basin (TLB), including an ecological ditch, a cement ditch and a soil ditch, in order to compare their differences in removal of total nitrogen (TN) and total phosphorus (TP) in a series of influent concentration and hydraulic retention time (HRT), the results showed that: in different conditions of HRT, influent flow or influent concentration, the removal efficiency of TN and TP of ecological ditch was significantly higher than other two ditches, while soil ditch was higher than cement ditch. In the static experiments the best of ecological ditch HRT was 48h.