In order to obtain the strain distribution law of arch rib of arch bridge under different stress conditions, the arch rib strain distribution under different loads is studied by establishing the finite element model and using the distributed optical fiber sensing technology based on optical frequency domain reflection(OFDR). The results show that the distributed optical fiber sensor based on OFDR pasted on the surface of the arch rib can not only accurately reflect the strain distribution law of the arch rib under different load conditions, but also obtain the strain distribution changes of the arch rib before and after the damage of the suspender, and locate the damage location of the suspender.