Abstract: Many accidents caused by corrosion have been occurred in Arshai oil pipeline since its production, which brought serious threatens to pipeline's safety operation. Using traditional experience and technology of positioning to carry out pipeline overhaul will not only act blindly in eliminating hidden danger of corrosion, but also result in overhaul cost increasing. The article introduces the principle of magnetic leakage detection technology and concrete application condition of it in Arshai oil pipeline. Performance of internal detection technology can not only detect hidden danger in pipeline accurately and provide guarantee for pipeline stable operation but also reduce pipeline overhaul cost compared with previous traditional positioning repairing due to precise detection and high accurate positioning, and it is of considerable economic efficiency.