The invention provides a lens protecting sheet fixing device and a video monitoring device. A fixing device comprises a tube body and a stop part, wherein the first end of the tube body is provided with a first flange projected towards the outer part of the tube body, the inner side wall of the tube body defines a protecting sheet accommodating cavity, and the stop part is detachably arranged on the outer side wall of the tube body. The inner side wall of the tube body defines the protecting sheet accommodating cavity, the first end of the tube body is provided with the first flange projected towards the outer part of the tube body, and through the matching of the stop part and the tube body, an object placed between the stop part and the first flange cannot freely move, so that the position limiting effect is achieved. The stop part is detachably arranged on the tube body, so the fixing device has the characteristic that the dismounting is easy. The fixing device mostly adopts clamp connection matching, and the matching precision between parts is reduced, so that the manufacturing process is simplified, and the manufacturing cost is reduced.