Abstract: The signalling pig and introduced intelligent pig (ϕ273 leakage magnetic flux pig) have been adopted in Xinjiang oil pipeline in order to detect pipeline defects. The detecting results show that the defects of pipe steel and the locations of internal and external corroded pipe sections have been found out accurately. Using the intelligent pig can cut down the pipeline accidents caused by corrosion and leakage, decrease upkeep period and cost, and is also helpful to the work-out of maintenance program.