In this paper, the life-table method was used to study the effects of different concentration Prorocentrum donghaiense on the durations of different development stages of Brachionus plicatilis and the characters of its population growth. The results showed that P. donghaiense had significant effects on the growth and development of B. plicatilis via prolonging the durations of the rotifer's embryonic development and pre-reproductive, shortening the durations of its reproductive and post-reproductive and its mean lifespan, and reducing its laying eggs and fecundity. The net reproduction rate and intrinsic increasing rate of B. plicatilis decreased significantly, in comparison with those of the control. B. plicatilis could maintain definite population increase in the presence of different concentration P. donghaiense.