The invention provides a tank bottom plate structure of a large storage tank. The tank bottom plate structure comprises a threaded barb iron pile and a welding cushion plate. The welding cushion plate is welded to the top end of the iron pile. By means of the tank bottom plate structure, tank bottom vacuum layer gaps can be effectively restrained, and therefore the purpose of preventing leakage of a tank bottom plate and the tearing accident of a full fillet weld is achieved.