AC electromagnetic field stress detection technology can achieve rapid screening of stress concentration areas in pipelines, but current AC electromagnetic field stress detection technology is limited to uniaxial stress measurement and cannot adapt to the identification of complex stress states in pipelines. This study integrates magneto-anisotropic stress detection technology to establish a theoretical pipeline plane stress model and a finite element simulation model. It designs an orthogonal stress detection structure with dual coil sets. Simulation results verify that under axial stress, the variation amplitude of the longitudinal magnetic flux density reaches 2.61 times that of the transverse direction. Verified through universal testing machine loading tests, within the tensile range of 200 MPa, the sensor′s output voltage exhibits a quantitative relationship with the angle between the stress gradient and stress direction, expressed as ΔU=K*εl-εhcos2θ. The conclusion confirms that this method breaks through the uniaxial detection limitation of traditional ACSM technology, achieves biaxial stress decoupling and principal stress direction determination, providing a new means for pipeline stress state detection.