Abstract: A series of experiments were conducted to evaluate the microalgal diets to the growth， development and reproduction of Acartia pacifica in order to define the most favorable diets for this species. It results that the concentration （carbon content, similarly hereinafter）1.70 μg/cm3， concentration rate 2∶1 induced highest metamorphosis survival rate （mean=92.62%）， the concentration 4.25 μg/cm3， concentration rate 1∶2 induced highest egg production （mean=47.1 egg·female-1·d-1）， the concentration 1.70 μg/cm3， concentration rate 2∶1 induced highest length of cephalothorax （mean=932.9 μm）， and the highest length of body （mean=1 252.3 μm）. The results suggested that concentration 1.70 μg/cm3， concentration ratio of 2∶1 is the optimal diet for the culture of Acartia pacifica．