In the proceeding of the CNC system, it is a valuable subject that how to locate the fault based on the function of the CNC system. To solve this problem, the method of searching in divided execution trace was introduced into the fault localization of the CNC system. This method divided the execution trace into two segments, searching the statements continually. At the same time, the Fuzzy Arithmetic was used to calculate the suspiciousness of the statements executed by these traces. After the integrated analysis, we could locate the faulty statements of the program. The experiment results indicated that this method was effective in locating the fault of the CNC system software.