A cab of a passenger boarding bridge comprises: an active floor body having a back end connected to the front end of a cabin and a front end provided with a notch that accommodates a downwards or upwards opened door of an aircraft; a flap disposed corresponding to the notch and movably connected to the active floor body, the flap being turnable relative to the active floor body between a first position in which the flap closes the notch and a second position in which the flap exposes the notch; and an actuating device for driving the flap to turn. The cab is mounted to a front end of a cabin such that it serves not only aircraft having doors to be opened leftwards or rightwards but also those having doors to be opened downwards. Also disclosed are a passenger boarding bridge having the cab and a docking method thereof.