In view of the application requirement of surface nondestructive testing of ferromagnetic workpiece such as hot rolled steel pipe and oil well pipe in service, a magnetic bridge displacement sensing method and a sensor array are proposed to realize magnetic imaging detection of surface morphology defects with certain spatial resolution. In this method, the sensor and the workpiece form the magnetic circuit together. The sensor uses a special compact array structure of magnetization, which could obtain better performance due to varied specifications. Firstly, with a time-sharing method, it reduces the interference between adjacent measuring points, and pulse magnetizes each single displacement measuring magnetic circuit in the array. Secondly, the magnetic field in each measuring magnetic circuit is sampled at intervals. The displacement value of corresponding positions is calculated. Through theoretical calculation and simulation, this study analyzes the resolving power under different basic lift-off, in the array sensor testing morphology distortions like grooves. The spatial resolution of imaging the measured surface is analyzed under the influence of the system′s scanning and sampling parameters. By experiment evaluation, the measuring range of this sensor array is 0. 2 ~ 7. 0 mm, and the B-y sensing characteristics fitting curve′s linearity is about 1% . In comparison, the pre-existing H-shaped magnetic bridge displacement sensor is in the range of 1 ~ 5 mm, and the linearity is about 2% .