The machining of circumferentially spaced holes is frequently needed in manufacturing. The length of the cutting tool path of a set of holes varies in accordance with its number of rings, its number of rays,the distance between holes, and so on. In order to improve machining efficiency and to reduce cost, without compromising quality, the machining process should be done based on the shortest cutting path. The mathematical models of ring cutting and ray cutting were established, the lengths of their paths were calculated respectively. A macro program in which the shortest paths could be automatically chosen for machining was written. The cutting tool path and the machining program for circumferentially spaced holes were thereby optimized, resulting in improved machining efficiency.