The invention discloses a clamping hoop used for mounting a signboard on a pole. The clamping hoop comprises a bar-type shell; a spring extending in the length direction of the shell is arranged in an inner cavity of the shell; slideways are formed in the two ends of the shell wall of the shell correspondingly; longitudinal slide rods capable of being in sliding fit with the slideways in the length direction of the shell are inserted in the slideways correspondingly; the two internal ends of the two longitudinal slide rods are fixedly connected with the two ends of the spring correspondingly; transverse rods extending towards nearby positions of the outer wall of the pole are fixedly arranged at the external ends of the longitudinal slide rods correspondingly; hinges capable of being bent to the outer wall of the pole are arranged at the ends, close to the pole, of the transverse rods correspondingly; and hooks in hooking fit with mounting holes of the signboard are fixedly arranged at the tails ends of the hinges correspondingly. The clamping hoop used for mounting the signboard on the pole has the advantages that the signboard can be fast mounted to the pole, operation is simple, only one person can complete operation, and the mounting efficiency can be improved; the signboard can be fixedly locked to the mounting position on the pole, fastening is firm and reliable, the signboard is not prone to sliding vertically or rotating around the pole and can adapt to poles with different diameters, and the universality is good; and the locking degree of the signboard and the pole can be adjusted according to the mounting environment such as factors of wind strength and the like, the rain-proof, wind-proof and rusting-proof performance is achieved, the service life is long, and the signboard can be locked to the pole for a long time.