Abstract: The influences of food concentration on populat ion fluctuation and production of cannibalism, Asplanchna brightwelli were studied. It was found that, in the cumulative culture , the population dynamic of A. brightwelli fed on Paramecium of concentrat ions ranging from 100 to 400cell#mL- 1 displayed typical 0s0 curves in the course of the experiment , and the relationship between the population persistence production and standing crop were conic function. With reference to food density experiments, there were the highest value of maximum sustained yield( MSY) , capacity ( K) , average production or intrinsic rates of increase of population under 300 Paramecium#mL - 1 in the whole diet concentration, which were 6. 4indiv#mL - 1#d - 1 ( 355mg#L - 1 ) , 13. 7ind# L- 1( 760. 6mg#L- 1) , 55 mg#L- 1 and 1. 4496( d- 1) respectively. In the range of 100- 300cell#mL- 1, the MSY, critical standing crops and the time arrival to MSY or K increased with increment of diet concentration, whereas the above ment ioned indexes decreased in 400cell#mL- 1 of food density. Fed on Paramecium, the value of food rat ion of rotifers changed 146% ~ 707% of body weight , with average 390%; food coeff icient was 19. 8 - 91. 7.