Aiming at the demand of the impact monitoring on stiffened composite panel, a fast impact load detection method based on distributed optical fiber grating sensing network is proposed. Optimization allocation of the FBG sensor is realized, different rank energy distributing trend of impact response signals are obtained by using the wavelet packet, the sample response matrix is constructed based on the ratio of the the amplitude ratio of the specific energy spectrum. Based on the above research, the impact detection of stiffened composite panel can be realized by BP neural network.