Abstract: The various damage mechanisms in 3D C/SiC composites were identified using acoustic emission (AE) signal parameters, and the Felicity effect was studied with tensile loading---unloading procedure. The effect of damage characterization on tensile behavior was investigated. As a result, the Kaiser effect is almost absent and the Felicity ratio decreases with the increase of the stress level and drops when the relative stress ratio is above 65%. The key factor of high performance of 3D C/SiC composite is not the amount of all AE hits but the time and quantity of major signals with higher energy and amplitude.The lower damage quantity is necessary to improv tensile strength of the composite during smaller deformation stage (strain<0.15%). The fiber cluster failure dispersion on bigger deformation stage is benificial to the enhancement of the tensile strength.