The invention discloses a bentonite grinding and screening device, which comprises a shell. A horizontally arranged opening is formed in an upper side wall of the shell; two vertically arranged support rods are symmetrically arranged on an upper side wall of the shell; a first drive motor is arranged on one side wall of one support rod; an output shaft of the first drive motor penetrates through aside wall of the support rod and is connected with a first rotary shaft arranged horizontally; a screw thread is formed in an outer side wall of the first rotary shaft; one side, far away from the first drive motor, of the first rotary shaft is rotatably connected with a side wall of the other support rod; a nut matched with the first rotary shaft is further sleeved on the outer side wall of thefirst rotary shaft; and a vertically arranged limiting rod is arranged on one side wall of the nut, and is inserted into the opening. The bentonite grinding and screening device provided by the invention can be used for thoroughly smashing bentonite and fully screening powder at the same time, and is high in automation degree, and higher in screening efficiency.