A campus broadcast device fixing system comprises a cuboid first box, a second box, a hinge, a plurality of rubber barrels, an air pump and connecting pieces. The inner side face of the first box is opened and is arc, and a plurality of independent dividing bins are arranged on the inner side face of the first box. The second box and the first box are the same in structure and are symmetrically arranged. The hinge is connected between the first box and the second box, and after the first box and the second box are folded through the hinge, a circular cavity is formed between the inner side face of the first box and the inner side face of the second box. The rubber barrels are fixed into the dividing bins of the first box and the second box. After the rubber barrels are inflated, the rubber barrels are in an arc cylinder structure. The air pump is connected with the multiple rubber barrels and used for conducting inflation on the rubber barrels, and the inflated rubber barrels protrude out of the dividing bins. The connecting pieces are arranged on the first box and the second box and used for connecting the first box with the second box. According to the campus broadcast fixing system, a broadcast device is fixed to a cylinder object, and no harm can be caused to the adhering cylinder object.