Abstract: The location principle for the negative-pressure wave technique of oil leakage detection system is de-scribed and the analysis and study on location failure of the system used in Dongying-Huangdao Oil Pipe-line are made. It is considered that this failure produced from the constant value designed for the transmis-sion speed of pressure wave of oil medium under the special conditions. So, the improvement on increasing the pressure point sampled, valve throttling to increase the input pressure of station and regulating the op-eration condition to eliminate the half-flowing is made and satisfactory results are obtained.