Abstract: Being fast, reliable, accurate, and needless to strip the outer coating of pipeline, the ultrasonic internal inspection technology has become an important means for pipeline non-destructive testing. Ultrasonic pipeline inspection technology abroad has undergone several decades development and put into a series of products. However, the corresponding research in China is still in initial stage. Compared with other non-destructive testing methods, ultrasonic inspection technology has advantages in detection precision and accuracy, and is a research hotspot in pipeline internal inspection. This paper analyzes the basic principle of ultrasonic inspection, introduces the existing research situation and the latest research at home and abroad, reviews the technical indexes and performance and characteristics of advanced ultrasonic detectors abroad at present. In addition, the developing direction of ultrasonic inspection technology in the future is pointed out, which can provide a reference to the inland research of ultrasonic internal inspection technology.