The utility model relates to a lateral refueling device, comprising a screw cylinder (4), a nozzle tip main body (1) forming the spiro union with a cylinder body, and a pair of screws passing through the inside of the screw cylinder. The utility model is characterized in that the lateral refueling device is arranged on the screw cylinder (4) on the position where the two screws are mutually meshed; a head face of an output port on the lower part of the nozzle tip main body (1) thereof is matched with an inner edge of the screw cylinder in the same cambered surface way; the head face of the output port of the nozzle tip main body (1) extends inside the screw cylinder, being higher than the inner cambered surface of the screw cylinder. Compared with the existing refueling device with the same function, because the position of the nozzle tip main body is moved from the upper sides of vertexes on the upper parts of the screws to the upper sides of the lateral faces of the screws, and the pressure generated by the lateral faces of the screws is smaller when the screws rotate, oily addition agent can be fed into the screw cylinder more easily, thereby providing the technical support to the normal operation and the stable product quality in the plastic extrusion technique.