FDJ (Flow Drill Joining) automatic tightening system for flow drill screws, referred to as FDJ. This is a set of intelligent equipment system adapted to multi-material connection, which is widely used in the connection of dissimilar materials such as ultra-high strength steel, aluminum-magnesium alloy, and composite materials, especially for closed cavity structures, which can operate on one side, with more efficient and lower costs, and is widely used in body-in-white, new energy and other industries.