Abstract: In recent years, alternating current field measurement (ACFM) technology has been widely used in non-destructive testing and quantitative evaluation of various structural defects. In order to solve the problem of misjudgment of defects caused by interference signals caused by probe jitter during defect detection, a novel differential detection probe is proposed. A finite element simulation model of ACFM probe is set up by COMSOL. The distortion law of the characteristic signals under lift-off jitter is investigated. The relationship between the Bx background magnetic field and the detection position is analyzed. Further, a probe based on differential magnetic sensors is designed. A defect detection system is built and related experments are carried out. The experimental results show that proposed differential detection probe proposed in this paper can effectively suppress the lift-off interference, enhance identification ability of the defect signals, and improve the detection sensitivity.