Based on the character of non- stationary signal，the feature of energy distribution in acoustic emission signals under impact loading was investigated by means of the wavelet packet method. Firstly, the characters of wavelet packet analysis were introduced. Secondly，eight signals were analyzed by wavelet packet based on software MatLab and the change of energy distribution curve at different frequency bands was obtained. Finally, the law of energy distribution of acoustic emission signals under impact loading was analyzed, and the influence of different rocks on frequency bands energy distribution of acoustic emission signals under impact loading was principally explored. The results show that frequency bands energy distribution of acoustic emission signals under impact loading was affected by different rocks，In other words, if the density of rock is less, the speed of the longitudinal wave is lower ,and the modulus elasticity is less, the dominant frequency bands of acoustic emission signals under impact loading become more energy-intensive and tend to be low；uniaxial compression strength and tensile strength have nothing with the dominant frequency bands of acoustic emission signals under impact loading.