Abstract: Long-distance oil and gas pipelines are subjected to the coupling effect of multiple factors such as geological disasters and pressure fluctuation of transported medium, which easily causes local abrupt stress variation. Pipeline stress inspection can effectively prevent pipeline failure and reduce or avoid the occurrence of safety accidents. Based on the basic theory of alternating current stress measurement (ACSM), this paper establishes the ACSM simulation model and explores the variation law of electromagnetic parameters under stress. Consequently, an alternating current field measurement(ACFM) probe applicable to pipeline stress detection is developed, and a pipeline internal inspection system is integrated. Static tensile tests are carried out on common pipeline steels including Q235, X60, X70 and X80. Experimental results show that as the increase of tensile stress, the magnetic flux density (Bx) signal shows a monotonically increasing trend along the direction of the applied magnetic field. Under different probe excitation parameters, the sensitivity of the Bx signal varies. With the increase of excitation frequency, the sensitivity of the Bx signal first increases and then decreases. The Bx signal is adopted to characterize stress. A mapping database between Bx signal and stress sensitivity is established for common pipeline steels. Combined with actual pipeline operating conditions and signal variation characteristics, a combined denoising method of amplitude limiting and smoothing is applied to realize signal noise reduction. Meanwhile, the quantitative evaluation of stress in abnormal regions is achieved, which provides a reference for the quantitative stress detection of long-distance oil and gas pipelines. Field tests are carried out on X80 pipeline steel pipelines with natural gas as the transported medium, then the 8-array probe and the stress detection electronic unit are mounted on a crawling device. The self-developed detection system is adopted to extract and analyze the measured data, and a total of 4 obvious stress abnormal regions are identified. This study verifies the feasibility of applying ACFM technology to quantitative pipeline stress detection, and provides reliable technical support for the safety early warning of long-distance pipelines.