Abstract: When locating the position of pipeline leaks with the traditional negative pressure wave (NPW) method, the inflection point of the sudden change of the pressure signal must be accurately obtained. If the inflection point cannot be obtained, then locating leaks is impossible. To overcome the shortcomings of NPW, we propose a nondestructive method of locating the position of a leak based on the change in the sound velocity of an ultrasonic signal. We establish the relationship between the position of a leak and the change in the sound velocity of an ultrasonic signal at the ends of a pipeline on the basis of the motion equation and the continuity equation in the transient flow equation of a pipeline. The localization of the leakage position depends only on the change in the velocity of the ultrasonic signal at the ends of the pipeline rather than the time difference of a NPW arriving at the ends of the pipeline. An analysis of the data obtained from leaks in an experimental loop pipeline shows that the proposed method can be applied to locate leaks, and the minimum error for leakage localization is decreased to 0.245%.