A gastrointestinal tract diagnosis device, comprises: an endoscope having a circuit module, the circuit module at least including a control unit and a recognition marker that are disposed on a substrate; an image capturing module at least including a first lens and an image sensor that are disposed on the substrate; an illuminating module at least including a first light source disposed on the substrate; an enclosure body assembled to a connection device to waterproofingly enclose the circuit module, the image capturing module and the illuminating module; and a work station connecting to the endoscope, so as to access the recognition marker and to add a machine identity into the recognition marker to match with the endoscope, wherein the work station determines if a usage state of the endoscope is overdue by a timer; and the work station determines if the endoscope has connected to an another work station different to the work station by the recognition marker and the machine identity. A method for forcibly disabling the function of the endoscope is provided in the instant disclosure, allowing the endoscope to become a disposable endoscope only for one-time checking. The threats of unusual infection and spreading of pathogen can be prevented and the problems of public health can be solved.