The invention relates to a tightening device for a two-way threaded projecting-gear sleeve of a reinforcement cage in a cast-in-place pile. The tightening device comprises an upper circular-ring movable tray and a lower circular-ring movable tray, wherein a tightening apparatus is arranged on each of the upper circular-ring movable tray and the lower circular-ring movable tray; the upper circular-ring movable tray is connected with an upper arc-shaped neck, and the lower circular-ring movable tray is connected with a lower arc-shaped neck; the upper arc-shaped neck is connected with an upper expansion connection component, and the lower arc-shaped neck is connected with a lower vertical support; vertical expansion steel bars are arranged between the upper expansion connection component and the lower vertical support, and a U-shaped reinforcement cage support frame is arranged in the middle of the lower vertical support; the gear sleeve is arranged at the end of a longitudinal steel bar of the reinforcement cage. The tightening device can realize mechanical connection and has a simple construction process, and the operation is less influenced by environmental factors. The tightening device meets the effective transfer of the longitudinal stress of the reinforcement cage while reducing waste of resources, saving cost and shortening the construction period.