A satellite can be damaged because its main component, a composite material honeycomb panel, is easily impacted by space debris and explosive devices. Monitoring the impact location is an important step to ensure the safe and reliable operation of satellites in orbit. A sensing system based on fiber Bragg grating(FBG) was built in order to monitor the impact signals of a typical composite honeycomb sandwich structure in real time. The wavelet packet energy spectrums of these impact response signals were analyzed, and the energy of 16th decomposition level was observed to be sensitive to impact and could thus be regarded as the feature values. Impact locations were predicted by means of the energy and amplitude ratio. The results showed that the average error for the test was 1.87cm. Thus, this method can effectively determine the impact position, which provides a strong basis for satellite structure health monitoring.