A quick installed joint assembly includes a fitting body, a sleeve, and an inlet pipe. One end of the chamber of the body communicates with a water supply pipeline, and the other end communicates with an accommodation part and passing through the fitting body. The sleeve is disposed within the accommodation part and has stopper portions. Each stopper portion has a wedge-like portion and a hook portion is extending outwardly from the wedge-like portion. The body has plural openings corresponding to each stopper portion, so that one end of the inlet pipe can pass through the sleeve and be inserted within the chamber. The inlet pipe corresponding to the bottom edge of the stopper portion has a large diameter portion for leaning against on the stopper portion, so the hook portion can be hooked on the openings and the inside wall of the accommodation part can support the wedge-like portion.