At temperature 24±0.5℃, the filtration rates of scallop Chlamys farreri spats (1.177～2.017 mm in shell length) were determined at different salinities (20,25,30,35) when microalgae density was 3.0×10⁴ cell/ml and different density of microalgae (Dicrateria zhanjiangensis) (3.0×10⁴ cell/ml, 4.5×10⁴cell/ml, 6.0×10⁴ cell/ml) when salinity was 30, using static water method. The relationship between the filtration rate (FRS) and the salinity (S) can be expressed byFRS＝-30.893S²+1 691.5S-196.10 (r=0.847) (calculated by whole dry weight), FRS＝-0.022S2 1.223 6S-14.522 ( r= 0.928, calculated by individual quantity) . We estimated that at the salinity of 27.8，the filtration rate reached the maximum value, 3.54L/g•dw•h（2.49×10^-4 L/ h•ind）. The filtration rate of the scallop spats increased with the salinity when the salinity was lower than 27.8 and decreased when it was more than 27.8. Feeding rate had significant influence on the filtration rates of the scallop (P< 0.05). When fed with D.zhanjiang ensis at in the concentrations of 3.0×104cell/ml, 4.5×104cell/ml, 6.0×104cell/ml, the filtration rate of the scallop spats increased and then decreased in a parabolic trend.It was estimated that the highest filtration rate(0.43×10^-3L/ h•ind)could be reached when the density was 4.7×10⁴ cell/ml.The relationship between the filtration rate (FRQ) and the microalgae density (Q) was FRQ=-0.069 3Q² 0.648 4Q-1.083 5(r= 0.722)。