A system for classifying tiny insects includes a cultivation tank, a detecting container, a detector, a gathering device, and a control unit. The cultivation tank is connected to the detecting container, so that the hatched tiny insects can enter the detecting area of the detecting container from the cultivation tank. The detector is used for detecting the characteristics of the tiny insects in the detecting area, and then the control unit controls the switching unit of the gathering device to switch the gathering containers for gathering the tiny insects according to the detecting results. The system of the present invention is capable of automatically classifying the tiny insects and then gathering them to different gathering containers according to their characteristics, so as to decrease the man power and time necessary for factitious classification.