Current study is aiming at making an in-depth research about the characteristics of the acoustic emission (AE) signals produced during the steel corrosion of reinforced concrete. Basing on the simplified waveform parameter analysis, a more effective method-frequency spectrum analysis for each waveform in time-domain is carried out to get more comprehensive and detailed AE signals' characteristics. The research shows that the accelerated corrosion process can be divided into four stages: inaction, onset, acceleration and deterioration. The combination of simplified parameter analysis and frequency spectrum analysis is shown successful for the research about the characteristics of AE signals in each phase. From these results, a great promise for AE technique to monitor the corrosion process in reinforced concrete is clarified. And the combination of different methods for signal analysis especially spectrum analysis is more reliable to the study about the characteristics of the AE signals.© (2011) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.