For the large space of sensor array in the alternating current field measurement (ACFM) probe, the spatial resolution of the measured distorted magnetic image is low above defects. As a result, the accurate morphology of defects cannot be reconstructed. In this paper, a novel ACFM probe array and testing system are set up based on the high resolution TMR magnetic field sensor array for the high-resolution imaging of distorted magnetic field. The finite element simulation model of ACFM is established. The induced electromagnetic field distortion law around the different defects is analyzed. The relationship between defect surface profile and magnetic field image is analyzed. The high-resolution sensor array is designed with 1 mm spacing. The range of uniform current field is analyzed by simulation. The multiplexing module is designed to preprocess the signal output from sensor array. The structure of the detection probe is designed. The testing system is set up to carried out defect detection experiment. The results show that Bz (magnetic field perpendicular to specimen) image and Bx (magnetic field parallel to probe scanning direction) image can reflect the information of the end point and edge of the defect respectively. The high-resolution magnetic field image of the distortion around the defect can be obtained by the ACFM probe arrry. The surface profile of the defect can be imaged visually accurately by the image of magnetic field.