China's oil and gas pipeline industry has achieved leap-forward development, and pipeline body defects and corrosion problems should be taken seriously. The oil and gas pipeline has fully enforced the integrity management procedures. The in-pipe inspection technology can determine the corrosion and crack defects of the pipeline and ensure the long-term operation of the pipeline. The system expounds the scope, advantages and disadvantages, technical status and application of the internal detection technology widely used in pipelines at home and abroad, including deformation detection, magnetic flux leakage detection, ultrasonic detection and electromagnetic ultrasonic inspection, and points out the types and defects of defects. The core issues of concern to the threshold, size quantization accuracy, and positioning accuracy, and the internal detector indicators should be verified through pipeline excavation and traction tests. Finally, the future development trends of in-pipe inspection technology, including crack detection and stress corrosion cracking (SCC) internal detection technology, eddy current detection and cathodic protection current detection technology are prospected.