Abstract: Aimed at these problems existing in seam tracking in narrow gap submerged arc welding, such as transverse seam tracking and tracking for both high position and low position, a novel electromegnetic sensor based on the principle of inductance was designed, which can scan the welding grove by the primary coil magnetic field and the collected current signal can be processed to derive the welding torch deviation and adjust the slider level movement for coping with the sidewall fusion. Through the variation of the secondary coil induction electromotive force, the location of welding torch can be obtained. The real-time identification of the relative height deviation of the welding torch can be used to track the bidirectional weld movement quickly and smoothly by using PID algorithm processing. The developed sensor has a simple structure with high sensitivity and strong anti-interference ability, therefore it provides a new solution to the thick plate of narrow gap submerged arc welding tracking.