Abstract: To study the micro mechanical behavior of steel fiber reinforced reactive powder concrete (SF/RPC) composite material under flexural loads, 10 experimental beams were fabricated and tested. Based on the acoustic emission technique, the acoustic emission signals and waveforms during the test were collected by using the broadband sensors. The acoustic emission parameters of SF/RPC material were analyzed, and the waveform spectrum was studied deeply on the basis of the signal processing of the waveform. The acoustic emission velocity of the SF/RPC material was measured by emitting and receiving signals between the sensors. The acoustic emission characteristics of normal concrete(NC) material were explored for comparison. The results show that the accumulate number of hits is much larger than that of NC beam under the same load, and the acoustic emission activity is higher than that of NC. The acoustic emission characteristic parameters of prestressed SF/RPC are obviously different from NC beam. The average acoustic emission hits proportion of SF/RPC for the short rise time period (<30 μs) is 64.2%, while the proportion of NC is 51.2%. The frequency domain characteristics of SF/RPC material are also significantly different from those of NC material. Before the load, the average wave velocity of SF/RPC is 4 342.8 mm/s, while the velocity of NC is 2 337.7 mm/s. The acoustic emission damage parameter (b_I) value is calculated based on the Gutenberg-Richter theory. The relationship between b_I value and the damage fracture process of prestressed SF/RPC was explored. This study provides experimental basis for the effective identification of the acoustic emission characteristics of SF/RPC material.