Abstract: Differential-pressure method is not a sophisticated tracing technique, since it is used predominantly as a passage indicator but has no capacity of positioning the block points. But, the method has high sampling frequency, so it has advantages in tracing of high-speed pig. With consideration to above problems and advantages, basic principles and on-site testing data of differential-pressure method are analyzed to determine feasibility of tracing high-speed pig by using the technique. In addition, calculation methods for positioning of stuck pig and methods to enhance positioning accuracy are proposed. Eventually, design program for remote on-line pig tracing and positioning system is proposed to eliminate impacts of environmental, weather, transportation and other conditions to conventional pig tracing operations.