In this system, Longi.'s Fillet Welding is performed at the same time that the Longi. which is tip-mounted on the mainboard is mounted automatically positioning during the manufacturing process of the panel assembly line, and this system maximizes the productivity due to shortening of work time and the cost reduction due to the complexity of the equipment compared to the existing equipment which performs mounting and welding separately and, because it is possible to work more precisely by attaching the welding line automatic tracking device and the edge detection device of the mainboard, it is a device that can maximize the quality improvement of products.