From March 1987 to March 1988, measurements were taken on the quantities of seston and particulate organic detritus in two areas of Baoan Lake, Dahu and Jiaodunhu. The average dry weight of seston was 337.6 and 100.5 tons in Dahu and Jiaodunhu respectively. The ash-free dry weight of seston was 127.7 and 50.3 tons in Dahu and Jiaodunhu respectively. The quantity of particulate organic detritus was 96.9 and 40.2 tons in Dahu and Jiaodunhu respectively, Showing apparent seasonal variations in the quantities of seston and particulate organic detritus. The decomposition of Potamoglton maackianus, Myrio-phllum spicatum and Vallisneria spiralis are important in the formation of seston. Estimated from the amount of carbon in the seston, the potential production of silver carp and bighead carp is 12.3 and 11 kg/mu at Dahu and Jiaodunhu respectively.