The invention provides a fermentation tank for bacillus thuringiensis to generate unit cells, the height-diameter ratio is from 2:1 to 3:1, and the cone bottom and the tank top are provided with ellipse heads; 2-4 jet flow mixers are arranged above the cone bottom of a tank body, the cone bottom of the tank body is provide with one cooling belt, and two cooling belts are arranged at the 1/3-2/3 above the cone bottom of the tank body; the tank top is provided with a safety valve, a vacuum valve, a vapor-liquid shunt interface and an overhaul inlet, the cone bottom of the tank body is provided with one discharge hole, and one discharge hole is respectively arranged under the two cooling belts at the upper part of the tank body; and the fermentation tank is matched with a normal fermentation tank to be specially used for performing the post-fermentation on fermentation liquid when germ is cultivated to form at first in the normal fermentation tank. Therefore, the energy consumption caused by the fermentation can be reduced, the yield of the germ and crystalloid can be improved, and the fermentation tank is good for separation of the crystalloid and the germ.