Impeller stirring device of fermentation tank

The impeller stirring device of the fermentation tank comprises a tank cover, a shaft rod and a plurality of impellers, the upper end of the shaft rod penetrates through the tank cover and is in running fit with the tank cover, each impeller comprises a shaft sleeve and a plurality of blades evenly distributed in the circumferential direction of the shaft sleeve, a notch is formed in the side portion of each shaft sleeve, and the blades are arranged in the notches. The shaft sleeve is provided with a notch, the notch penetrates through the upper end and the lower end of the shaft sleeve, the shaft rod penetrates through the notch and is clamped in the shaft sleeve, a protruding key is formed on the inner wall of the shaft sleeve, a key groove is formed in the side wall of the shaft rod, and the protruding key is clamped in the key groove. Compared with the prior art in which a pin is adopted for fixing, not only is the assembly step simpler, but also the impeller is easy to design and manufacture, the situati