Abstract: In order to solve the problem of pipeline deformation and buckling caused by the difficulties in measuring the bending stress of oil and gas pipelines, a bending stress detection method based on magneto-elastic effect was proposed. Firstly, the magneto-elastic stress detection model was established. The relationship between magnetic circuit and impedance characteristics in the detection loop of magneto-elastic sensor was also analyzed. Secondly, the stress distribution within the material under bending was studied. Finally, the relationship between the impedance and stress in Q235 steel plate during bending under different conditions was experimentally investigated. Results show that the impedance on the steel plate surface apparently declined with increasing stress and the relationship between impedance and stress within a certain range of stress was approximately linear. Within a certain range of stressed area, the impedance change with stress can be detected. This proposed method can effectively achieve pipe bending stress detection. The experimental results and theoretical analysis are in rather better agreement.