The invention discloses a plaster cutting packaging method and device. The method comprises the steps that a packaging film is cut to form an upper packaging film and a lower packaging film; plaster materials are cut into plastic sheets; front and reverse face overturning is performed on the lower packaging film, the upper packaging film, the plastic sheets and the lower packaging film which are sequentially arranged from top to bottom are fed into a mold sealing and pressing device at the same time for sealing and pressing packaging to form continuous plaster bags; and edge cutting and slitting processing are performed. The device comprises a packaging film unwinding and slitting device, a plaster material unwinding and slitting device, the mold sealing and pressing device, an offcut slitting device and a small bag cut-off and output device which are arranged on the machine frame. The outlet end of the packaging film unwinding and slitting device and the outlet end of the plaster material unwinding and slitting device are connected with the inlet end of the mold sealing and pressing device. The mold sealing and pressing device, the offcut slitting device and the small bag cut-off and output device are sequentially arranged in the plaster bag conveying direction. The packaging technology with the high automation degree can be achieved, production is stable, and the production efficiency is high.