Due to the remarkable technical advantages, magnetic flux leakage testing (MFL) is widely used in nondestructive testing of ferromagnetic components, especially in the field of internal inspection of oil and gas pipelines. The spatial resolution of MFL inspection is determined by the sensor arrangement density. However, the sensor arrangement density is limited by its size, especially for single-row sensors. Therefore, to improve the spatial resolution for the inspection, the multi-row and staggered arrangement of sensors is a simple and feasible method. Due to the different background magnetic fields at the positions of multiple rows of sensors, the influence law of different background magnetic fields on the detection signal is not clear. Therefore, it is necessary to carry out a theoretical analysis of the above problems. A method is proposed to correct the detection data of multiple rows of sensors. Based on the magnetic charge theory, the defect detection signal is divided into the superposition of the background magnetic field and the defect leakage magnetic field, and the superposition rule of the two is given. Based on this, the method of correcting the detection data of multiple rows of sensors is proposed. The effectiveness of the proposed method is evaluated by COMSOL simulation and experimental results.