The invention discloses a safe plate cutting device which comprises a detachable a cutting machine body installed on the end surface of the bottom of a moving hoisting seat. The novel safe plate cutting device is characterized in that the cutting machine body is internally provided with a first sliding cavity with a downward opening and a first lifting cavity, with a downward opening, which communicates with the first sliding cavity; a lifting frame is installed in the first lifting cavity in a sliding and matching manner; a lifting drive mechanism is arranged in the inner wall body of the cutting machine body and at the right side end of the lifting frame; a second sliding cavity is arranged in the lifting frame; a sliding seat is installed in the second sliding cavity in the sliding andmatching manner; a rolling groove which extends from left to right is arranged in the upper end surface of the sliding seat; a buffer mechanism is installed in the second sliding cavity on the upper end surface of the sliding seat in a manner of pressing against and being matched with the rolling groove; and a depression cavity is arranged in the end surface of the lower part of the sliding seat.The device is simple in structure and convenient to operate, effectively prolongs the service life and effectively improves the safety.