Residual feed and faeces were calculated according to the research on feeding rate and faeces rate of Japanese sea peach Lateo labrax japonicus cultured in the net cages in Xiangshan Bay.The result showed that the average feeding rate of Japanese sea peach was 2.6%(wet weight) or 0.6%(dry weight).The wet food scattered in the net cages was 143 335.5 tons a year,392.7 tons a day.The food(dry weight) that was scattered in the net cages was 31 045.5 tons a year,85 tons a day.The average excreting rate of sea peach(as dry particle organic carbon) was 6.5%.The calculated faeces quantity(dry weight) of the fish cultured in the net cages in Xiangshan Bay was 7.5 tons a day,2 737.5 tons a year.Average feed utility of Japanese sea perch was 71.8%.The wet residual feed was 43 252.5 tons a year,118.5 tons a day.The dry residual feed was 9 548.4 tons a year,26.16 tons a day.That showed the residual feed and faeces seriously polluted the quality of bottom and water in Xiangshan Bay.