Abstract: When the oil and gas pipeline is promoted by soil to produce uneven deformation, there will be hidden dangers to safety, so it is necessary to evaluate the online safety margin of the pipeline. In this paper, based on the acoustic-elastic theory, the stress theory and method of testing deformed pipeline under operating conditions based on ultrasonic method are studied, and the special device for on-line stress ultrasonic measurement of oil and gas pipeline is developed independently. In this paper, a set of stress measurement technology under pipeline operating condition is studied, and the field engineering application is tried. The results show that this technique is an effective means to measure the on-line stress of deformed pipe section, and provides reliable data for quantitative evaluation of pipeline safety margin and repair quality.