A process for machining a pull ring mold mainly relies on working procedure selection and arrangement, selection of a cutting tool, control over machining allowances, the rotating speed of a spindle and the feeding speed, and detection steps performed between key steps. The process includes the steps that a, vacuum heat treatment is conducted on mold steel, so that the hardness of the steel reaches HRC 58-60; b, the machining allowance of 0.3 mm is reserved, a blank is machined into an outer square shape through an accurate grinding angle rule, and the machining precision reaches the range within 0.01 mm; c, a part machined in the previous step is used as a positioning datum plane, semi-finish machining forming of an inner outline is conducted, a ball cutter is adopted, the machining allowance of 0.5 mm is reserved, and the rotating speed of a machine is controlled to range from 20000 r/min to 21000 r/min; d, vacuum heat treatment is conducted, so that the hardness of a workpiece reaches HRC 58-60; e, an outer square outline is machined through a hexahedral angle rule, the allowance of 0.02 mm is reserved, it is guaranteed that the requirements for the parallelism and perpendicularity of the part are both in the range within 0.005 mm, and the perpendicularity of the upper surface and the side surface is smaller than 0.003 mm; f, a numerically-controlled machine tool is adopted for clamping, the superhard ceramic cutting tool is selected, the rotating speed of the machine is 25000 r/min, the feeding speed is 1200 mm/min, and the tool is moved according to a procedure; and g, precise forming grinding is conducted on the shape until the shape is within the dimensional tolerance.