The disposable protective device for suction tube includes an encapsulating bag unit and a connective tubular unit. The encapsulating bag unit has a protruding circular portion. The encapsulating bag unit has an interior space which may house a suction tube. The encapsulating bag unit has a first opening and a second opening at its two ends, with the diameter of the second opening larger than or equal to that of the first opening. The connective tubular unit has a first connector, a second connector and a third connector. The first connector may connect with the second opening. A cover may cover the first connector. The second connector may connect with a ventilator. The third connector is provided at the bottom part of the connective tubular unit and may connect with a tracheostomy tube or a tube inside the trachea.
