In recent years, with the development of materials science, the joining technology is also constantly upgraded, ultrasonic testing technology can more accurately detect the defects or failures of new materials in the new joining process, which has extensive applications in the field of engineering joining, such as welding, mechanical joining, and adhesive bonding. This paper introduces the common non-destructive testing techniques, including magnetic particle testing, eddy current testing, penetration testing, radiographic testing, and ultrasonic testing. The main principles and devices of ultrasonic testing are introduced, including air-coupled ultrasonic testing, electromagnetic ultrasonic testing, laser ultrasonic testing, and so on. The current status of the application of ultrasonic testing in welded joints, riveted joints, bonded joints, and bolted joints is summarized and reviewed. Finally, the drawbacks of ultrasonic testing in this field are discussed, as well as prospective research directions.