Abstract: Aiming at the problem of welding quality degradation caused by the expansion of workpiece gap and the increase of two-layer plate thickness after robot servo welding gun passing through multiple welding spots in the process of resistance welding of the car door wing plate, the heat conduction numerical simulation analysis of resistance welding process of B180H1 baking hardening steel plate was carried out by ANSYS finite element technology, and the influence of plate’s thickness on welding heat conduction efficiency and nugget diameter were explored.Using the FANUC servo welding gun’s dynamic detection function for plate’s thickness and the macro program jump instruction, the robot welding procedure stopped and alarmed in time when the limit value of the plate thickness was exceeded, so as to reduce the defects such as spatter and false welding caused by the increase of plate’s gap, improve the nucleation quality and welding accuracy, and ensure stability of welded joint quality before and after resistance welding of car door wing plate.Highlights:(1)Finite element technique was used to analyze heat conduction of welding process.(2)The dynamic detection function was used to measure actual thickness of welding plate in real time.(3)According to actual thickness of the detected welding plate, the macro program was used to jump to ensure welding quality.