Flat milling machining auxiliary tool

The utility model belongs to the technical field of mechanical clamps, and particularly relates to a milling and flattening auxiliary tool which comprises a main fixing plate, a limiting piece and a pressing piece, a sliding groove is formed in the top face of the main fixing plate, a plurality of inserting grooves are formed in the positions, on the left side and the right side of the sliding groove, of the main fixing plate in a penetrating mode, and cylinders are inserted into the inserting grooves in a matched mode. The limiting piece and the pressing piece can be installed on the inner side of the sliding groove in a matched mode, the limiting piece is of a cuboid structure, a plurality of moving grooves are formed in the top face of the pressing piece, a rubber layer is fixedly bonded to the inner side face of each moving groove, and a polished rod and an inner threaded pipe are fixedly arranged on the bottom face of the pressing piece. The polished rod and the internal threaded pipe are slidably insert