Abstract: In order to meet the requirements for efficient and reliable detection of drill pipe connection threads, a magnetic perturbation detection method for drill pipe connection threads was proposed in view of the deficiencies of the existing detection methods and devices. The influence of the geometric parameters of the permanent magnet and the lift-off distance on the magnetization state of the thread root was simulated and analyzed by COMSOL software, and the optimal permanent magnet characteristics were obtained. According to the characteristics of the variation of the thread curvature, a multi-degree-of-freedom self-adaptive probe tracking mechanism was designed for detecting the inner and outer threads of the drill pipe connection, respectively. The detection speed is 30 s/piece, and the minimum detection depth is 0. 15 mm.