The invention discloses a soybean smashing device which comprises a supporting frame, a first connecting rod, a first smashing box, a second smashing box, a feeding pipe, a first rotary shaft, a first motor, a rotary wheel, a smashing plate, a smashing shaft and a second motor. The head end of the first connecting rod is eccentrically mounted on the rotary wheel, and a push rod is hinged to the tail end of the first connecting rod. The tail end of the push rod is connected with the smashing plate. A guide sleeve is mounted on the inner wall of the first smashing box. A drawable plate is transversely mounted at the position, below the feeding pipe, of the first smashing box in an inserted manner. A mounting groove allowing the head end of the plate to be mounted therein in an inserted manner is formed in the inner wall of the first smashing box. A discharging pipe is mounted at the bottom of the right side of the second smashing box. A plurality of cutters are mounted on the peripheral wall of the smashing shaft. A spiral screw piece is further mounted on the peripheral wall of the smashing shaft. The smashing shaft is in a circular truncated cone shape, and the diameter of the transverse circular face of the right end of the smashing shaft is larger than that of the transverse circular face of the left end of the smashing shaft. The soybean smashing device can fully smash soybeans, and the soybean smashing effect can be improved remarkably.