In response to the high probability of small hole leakage in complex coal to oil plant areas and the unsuitability of commonly used leakage detection methods for complex plant areas, as well as the difficulty in accurately detecting and identifying small hole aperture leaks, a judgment method based on process parameter combination changes and detector response data fusion is proposed; The occurrence of small hole leakage in different pipe sections will cause different parameter changes. Based on the combination of parameter changes, the interval where the small hole leakage occurs is determined. Combined with the response time of the detector during simulation, the detection range is used to determine the pipe section where the small hole leakage occurs. Combined with the intersection area, the position of the small hole leakage interval is determined. This method can timely determine the interval where the small hole leakage occurs, and timely investigate and handle small hole leakage accidents, which is of great significance for controlling accidents and avoiding accident evolution. Through example analysis, this method can effectively shorten the interval position of the small hole leakage pipe section, save investigation time, and can be used to determine the interval position where small hole leakage occurs in complex coal to oil plant areas.