The invention discloses a feeding device for an injection molding machine. The feeding device comprises an outer cavity. An inner cavity is connected into the outer cavity in a sleeved manner. Stirring rods are fixedly connected to the periphery of a rotating shaft. Scrapes are fixedly connected to the two ends of each stirring rod. An upper cover is fixedly connected to the top of the inner cavity. A weighing ring is arranged on the surface of the upper cover. A display screen is arranged at one side of the weighing ring and located on the surface of the upper cover. An electronic scale is arranged inside the weighing ring and connected with the display screen. By means of the feeding device, materials added into a cavity can be weighed; after being weighed, the materials can be automatically added into the cavity; the materials in the injection molding machine can be controlled conveniently; automatic feeding can be achieved; the materials added into the cavity can be stirred uniformly; the internal content uniformity of the materials is guaranteed; and the materials in the cavity can be thoroughly conveyed and prevented from adhering to the inner wall of the cavity.