Positioner used for installing tunnel arch center

The utility model discloses a positioner used for installing a tunnel arch center, which is beneficial to the fast installation of the arch center and the guarantee for the installation quality of the arch center. The positioner comprises a group of positioning arch centers arranged on an arch part at a tunnel inlet, connecting structures, substrates and positioning structures provided with datum planes, the positioning structures are longitudinally arranged along a tunnel, two adjacent positioning structures are connected with each other through the connecting structure, the datum planes of the positioning structures are positioned on a same sloping surface, the bottom surfaces of the positioning arch centers are provided with the substrates, and the substrates on the bottom surfaces of the positioning arch centers are connected with the datum planes of the positioning structures. The positioned further comprises a supporting arch center arranged on the arch part in the tunnel, wherein the bottom surface of