Abstract: Aiming at the problem that the oil and gas transmission pipeline exhibited the great safety hidden trouble after being occupied, and there wasnt any mature and reliable technology to detect occupied pipeline home and abroad, the paper carried on the detection experiment for eight selected sections of one  529 mm crude oil pipeline by the Wavemaker G3 ultrasonic guided wave detection system. The results showed that the single detection distances were 10~15 m for the buried occupied pipeline by the ultrasonic guided wave technology, and the 100% comprehensive detection and analysis could be carried on for the pipelines that the occupied distances were less than 30 m. The paper analyzed the harmfulness for pipelines after being occupied by expressway, high-rise building, and common bungalow, etc. by using detection results, and proposed the suitable recommend measures.