In this study, the three-point bending process of needled C/C composites, pack cementation SiC coated-C/C composites (PC-SiC-C/C) and chemical vapor deposition SiC coated-C/C composites (CVD-SiC-C/C) were monitored by the acoustic emission (AE) technology. To study the bending damage evolution process of three kinds of composite materials, the K-means algorithm was used to analyze the AE characteristic parameters. The damage type was analyzed by combining the electron microscope image of the sample fracture. The findings revealed that C/C composites and CVD-SiC-C/C composites contain three distinct types of damage: matrix cracking, carbon fiber-pyrolytic carbon interface debonding, and fiber fracture under three-point bending loading. PC-SiC-C/C composites has two additional damage: coating cracking and pyrolytic carbon-SiC interface debonding. The various damages could be identified by different AE signals: matrix cracking (175.781–421.875 KHz), carbon fiber-pyrolytic carbon interface debonding (70.312–164.062 KHz), fiber fracture (2.929–46.875 KHz), coating cracking (375–585.937 KHz), pyrolytic carbon-SiC interface debonding (169.921–257.812 KHz). The cumulative AE energy shows that the order of damage types of the three composites during the three-point bending loading is different.