Abstract: This paper deals with the concentrations and distributions o f nitrogen and phosphorus in the sediment and interstitial water in Baoan Lake i n August and October 1996. The mean concentration of N in the sediment was 5.20m g/g (D.W.) The concentration of N in the sediment in horizontal distributions at Qiaodunhu region was highest. The mean concentration of p in the sediment was 0 .75mg/g (D.W.). The concentration of P in the sediment in horizontal distributio ns at Biandantang region was highest.The mean concentration of TN in the interstitial water was 3.63mg/L. TN existed mainly in the form of ammonic nitrogen, which amount to 57.2% of the total. The mean concentration of TP in the interstitial water was 0.098mg/L, of which 50.0% was orthophosphate. The concentration of nitrogen and phosphorus in the interst itial water were inconspicuous in horizontal distributions. Except for ammonium nitrogen, the concentrations of nitrogen and phosphorus in i nterstitial water were generally within the range of five times higher than thos e in the mud. Thus, there is an intensive nutrient exchange between sediment and water in the lake.