Lathe auxiliary jig

The utility model relates to a lathe auxiliary jig, to be specific a lathe auxiliary jig used for processing the non-cylindrical work piece. The lathe auxiliary jig comprises a jig body, and is characterized in that a boss of three-pawl chuck capable of clamping on the lathe is disposed on the rear part of the jig body, and a pressing plate penetrating through a pressing screw is disposed on the front part of the jig body. The center of the jig body is a disc, which is concentric with the shaft of the lathe, besides, the front part of the jig body is provided with a positioning element. By using the utility model, the lathe can be used to process the non-cylindrical work piece.