The invention discloses a universal adapter. The universal adapter comprises an outer loose preventing sleeve, a rotating piece groove, a first loose preventing connecting sleeve, a second loose preventing connecting sleeve and a rotating piece. The rotating piece groove and the rotating piece which are connected in a clamped manner and are matched can rotate circularly in the peripheral direction, leakage of a hose due to excessive twisting of the hose when the angle is adjusted can be prevented, the first loose preventing connecting sleeve and the second loose preventing connecting sleeve are used for limiting axial movement of the rotating piece relative to the rotating piece groove, the outer loose preventing sleeve sleeves the outside of the first loose preventing connecting sleeve and the outside of the second loose preventing connecting sleeve, and therefore the first loose preventing connecting sleeve and the second loose preventing connecting sleeve are assembled and retained together and are restricted in the outer loose preventing sleeve. The universal adapter is novel in structure and convenient to assemble. Connection application under the working pressure of 25 Mpa and the nominal pressure of 50 Mpa can be realized by the universal adapter. Parts, which are connected with the rotating piece, of the rotating piece groove can be processed into movable sleeve joints, and the universal adapter can be matched with hoses of various factories, and is quite high in applicability.