In order to detect pipeline spanning and adapt to the fast-moving state of in-pipeline detectors in the field and the low power consumption requirements of stress sensor arrays, this paper proposes a method of measuring the pipe wall stress based on magnetoelastic under weak alternating current. Firstly, stress characteristics of spanning pipeline are studied via finite element simulation, and the stress sensor deployment scheme is determined. Secondly, steel stress measurement model of electrical impedance method is established, and stress sensor is designed and fabricated. Finally, experimental verification is carried out. The results show that the axial stress at the top and bottom of the pipeline can sensitively characterize the spanning pipeline state; when the elastic stress varies from 0~ 50 MPa,the sensor coil impedance and the stress have a negative linear relationship, and the linear fitting goodness of the sensitivity coefficient is greater than 0. 92; the sensitivity increases as the excitation frequency increases, and when the excitation frequency is 30 kHz, the average sensitivity coefficient is -0. 018 Ω/ MPa; the power consumption of a single sensor is less than 0. 1 mW