In order to get accurate and feasible seismic safety evaluation of a real dam, a self-developed miniature fiber bragg grating (FBG) strain sensor is used in this dam model experiment. By analyzing residual strain and peak strain produced by miniature FBG sensor in different magnitude, internal deformation and cracks of the dam model can be monitored, then seismic ability of the dam can be evaluated. The results of the experiment show that FBG sensor has high sensiti vity and good anti-interference ability. It can monitor internal deformation and cracks of the dam model timely and accurately, then identify and warn structural damages. Through comparing concrete deformation and cracks produced by reinforced dam and unreinforced dam, it shows that steel bars embedded in the dam’s weak position can restrain creation and development of cracks effectively and improve the anti-seismic capacity of dam significantly. The results of the experiment provide important basis for engineering design and the evaluation of dam anti-seismic ability.