Abstract：Combining with the Flexural-Tensile tests of wet sieving and three-graded concrete in Xiaowan arch dam., feature parameters and waveforms of acoustic emission (AE) signals during the whole process of third-point flexural-tensile are acquired using full-digital acoustic emission system. The development of acoustic emission activities in each loading stages is analyzed, the statistical features of peak frequency and frequency centroid calculated from FFT power spectrum are compared, damage mechanisms are identified based on the acoustic emission parameters, and the extent of the localized failure zones of microcracks are also compared using commercial software of AEwin, the following characteristics are found in three-graded concrete comparing with wet sieving concrete: (1)Easier to induce damage, and lower b value is observed in each loading stages; (2) The peak frequency of hits also appear in the frequency band of 100-125kHz and 225-250kHz, and the distribution of frequency centroid tends to lower than wet sieving concrete; (3) The duration ranges of two specific mechanisms identified in three-graded concrete are covered by one duration range in wet sieving concrete; (4) it showed a wider localized zone of microcracking than wet sieving concrete.