Based on acoustoelasticity theory, the relationship between ultrasonics and stress in oil and gas pipelines is researched. Further, the principle, method and technology of ultrasonic critically refracted longitudinal waves are analyzed. In order to ensure accuracy of test results and realization of quantity traceability, the calibration technology of ultrasonic testing for residual stress is studied. Then the ultrasonic stress testing and calibration system is established. For in situ regulation of residual stress, the interactive relationship between high energy ultrasonics and the residual stress field is studied. It is seen that the surface and internal component residual stress states are changed by effective control of the high energy beam and excitation mode. Finally, the in situ reduction and control of local residual stress distribution in mechanical components in service is realized. Thus, the whole strength, anti-fatigue and corrosion resistance of mechanical components in service are improved, and the service life, safety and reliability of components are also enhanced. This technology now is used in testing and regulation of oil and gas pipeline welding residual stress.