Abstract: Leaking, once happening to pipeline, will threaten the safety of pipeline operation. In order to find out the leaking location as quickly as possible, many a way is implemented at the same time in practice. Of many methods to delect leaking, the hydraulie gradient one is a well-known simple and easy method, in which the corresponding hydraulic gradient is calculated on basis of the throughput parameters at both upstream and downstream pump stations. The intersection of the two gradients is the leaking location being looked for. However, the accuracy of the measured parameters will be affected by oil viscosicy, specific weight and the precision of the metcring instruments. It is stated in the aricle that two extremums, the maximum and minimum ones of the three types of meters at up-and-down stream pump stations and combined into 64 combinations of which two combinations are selected by complex calcualtion with a computer, which decide the extremum at up-and down strcam stations. Meanwhile, here is Presented "the Programme Molds for Leakiug Detection" to facilitate pipcline design and management via soft ware.