Abstract: According to the characteristics of drilling packing box cover parts 6-Φ13.5 through hole and the actual situation of the factory, the traditional and offset indexing device has changed the previous way of clamping, and a simple special fixture with indexing device, positioning mandrel and fast assembly and disassembly is designed. According to the requirements of the packing box cover parts, the machining process is designed to make it a qualified product from the casting; among which, the tenth process step is designed to drill 6-Φ13.5 through hole, using a circle and one side positioning to limit five degrees of freedom, and using the spring pressure plate and the eccentric handle to clamp. Then the spring is used to locate the top rod and process it. Compared with the previously commonly used fixtures, the fixture can effectively reduce the length of the twist drill tool used in drilling; it is simple and convenient, which could save time and improve its production efficiency, and it is extremely feasible.