Abstract: Composite materials are more and more widely used in aerospace because of their superior performance compared with metal materials, whereas they are very sensitive to impact loads, so it is necessary to achieve long-term impact monitoring and evaluation. In this paper, after the analysis of the contact model of impact response, the impact signal model and the analysis parameters are selected, the slope of frequency amplitude spectrum is proposed as the characteristic analysis parameter for monitoring and evaluating the impact signal. Finally, the measured impact signals of fiber Bragg grating (FBG) are analyzed by establishing the impact test experimental system. The results show that the slope of frequency amplitude spectrum of impact signal can effectively analyze the energy change caused by impact distance, and evaluate the location information of impact relative to FBG.