Abstract: Concentrations of organochlorine pesticides (OCPs), HCHs and DDTs in water and the aquatic plant Potamogeton crispus L. were investigated from 29 March to 25 May 2008 in the main stream of the Haihe River. The results showed that the concentrations of HCHs and DDTs were in the range of 3.95-20.15 ng/L (mean 11.11 ng/L) and 6.88-35.23 ng/L (mean 15.34 ng/L) in water, and 2.17-7.82 ng/g (mean 4.49 ng/g) and 1.40-22.80 ng/g (mean 7.79ng/g) in Potamogeton crispus L., respectively. Concentrations and PCF of HCHs and DDTs in Potamogeton crispus L. reached the highest value during the Potamogeton crispus L. blooming period, and concentrations of HCHs and DDTs in Potamogeton crispus L. were correlated significantly to those in water. γ-HCH was the dominant HCH isomer in Potamogeton crispus L., while β-HCH was the dominant form of HCHs in water. Among DDTs, DDT was the most dominant compound in both water and Potamogeton crispus L., though the percentage of DDT was significantly lower in Potamogeton crispus L. This revealed that further biodegradation of DDT occurred in Potamogeton crispus L. and mainly under aerobic conditions.