The invention discloses a flat top tower crane effectively reducing the dead weight of a boom. The flat top tower crane comprises a bottom plate, a reinforcing rod structure, a connection frame and asliding frame; the middle part of the top end of the bottom plate is provided with a supporting frame; the outer wall of the supporting frame and the top end of the bottom plate are provided with reinforcing supporting frames respectively; the top end of a connection body is provided with a lifting frame; the top end of the lifting frame is provided with a reinforcing frame; the bottom end of thelifting frame is provided with the sliding frame; and the bottom end of a moving device is provided with a hook through a hoisting rope. For the flat top tower crane provided by the invention, by arranging the lifting frame, the sliding frame and connection rods, fixing and connection between the sliding frame and a reinforcing rod are reinforced, so that the structure is reasonable, and fixing and connection are stable; and by arranging steel rods, a galvanized round pipe and a sealing rubber sleeve, the steel rods are comprehensively protected, so that the steel rods cannot react with waterin air, and the protection performance of the steel rods is reinforced.