<p>The nondestructive testing (NDT) method of adjustable weak magnetic excitation is widely used in the field of long-distance oil and gas pipeline inspection, which plays a crucial role in the early identification of pipeline stress damage and accident prevention. This manuscript focuses on weak magnetic excitation nondestructive testing, establishes the finite element simulation model of oil and gas pipeline, utilizes the force-magnetic coupling model to study the characteristics of the signal and its changing law of the stress concentration under different weak magnetic excitation intensity and stress level, and verifies it through experiments, which provides certain references for engineering applications. The results indicate that an increase in the size of the stress concentration region correlates with a higher axial single peak value and a greater radial double peak value, both of which exhibit a linear increasing trend. Furthermore, as the weak excitation strength is augmented, the excitation signal concurrently intensifies. The above study can provide a theoretical reference for the change of the state of long-distance oil and gas pipelines under the influence of multiple factors, so as to provide a certain reference for exploring the optimal excitation interval for in-pipe detection.</p>