The invention discloses a tank cover automatic feeding mechanism, and belongs to the field of metal material machining mechanical equipment. The mechanism comprises a conveying support, a conductive motor, a conveying belt, a cover discharging hopper and a cover guiding mechanism, wherein the conductive motor drives a main guide belt roller, the conveying belt is sequentially wound around and connected with an upper guide belt roller, the main guide belt roller and a lower guide belt roller, and a plurality of upper cover plates are horizontally arranged on the outer side of the conveying belt in the conveying direction in sequence; the cover discharging hopper is horizontally arranged on one side of the conveying support, and the lower side of the cover discharging hopper is obliquely downwards and provided with a cover guiding plate; a leakage-proof rubber sheet is horizontally arranged between the lower side of the cover guiding plate and the conveying belt; an air inlet guide pipe is horizontally arranged on one side above the conveying support, and the cover guiding mechanism comprises a cover guiding support, an adjusting support and a cover blocking rod. The tank cover automatic feeding mechanism is reasonable in structural design, tank covers can be rapidly and efficiently fed and stably conveyed one by one, the machining efficiency and quality of the tank covers are improved, and requirements of production and use are met.