Abstract: Considering the misalignment in sheet butt joint and the difficulty in tracking lap joint, a weld seam tracking method was proposed based on variable-area-typed dual eddy current sensor. The weld seam tracking was realized with mutually compensated independent deviation signal, by detecting level and horizontal location information, respectively, with two variable-area-typed eddy current sensors put on one side of the weld seam. The principle of variable-area-typed eddy current sensor was analyzed. The response surface was fitted by using responsesurface method, and the variables were separated to obtain the relation between the area and the output voltage signal. Finally, a simple platform was established to conduct seam tracking experiments during thin plate butt and lap welding. The results verify the feasibility and accuracy of the weld seam tracking method with variable-area-typed dual eddy current sensors, providing a new research field for automatic weld seam tracking technology.