The AE signals from steel fiber reinforced concrete, normal concrete and mortar beams during the entire fracture process were recorded and analyzed. The filter was set on the AE signal duration based on the characteristics of the distribution of AE signal amplitude. According to the value of AE signal amplitude which corresponds to the occurring of peak for AE hits, the AE signals from mortar, normal concrete and steel reinforced concrete were divided into five, seven and nine sections respectively. The failure mechanism of concrete was also analyzed from micro structure and the relationship between the AE signal sectin and the failure mechanism was set up. Based on the experiments, the AE characteristics of each failure mechanism were given. The results showed that AE technique is a valuable tool to study the failure mechanism of concrete materials.