In order to ensure that the piston motion with sufficient clearance process, processing avoiding valve pits in their head are in need. Such as rounded corners from the pit avoiding valve piston, for example, in the process of machining using MasterCAM software, various parameters were set, and machining process was programmed, which resulting machining numerical control (NC) code as required in practical machining. In the process of programming, two different programming methods were used, and its impact was analyzed in the manufacturing process of piston valve for avoiding pits. So the most appropriate of the pits avoiding valve of rounded corners processing method is determined.