Plain plate specimens of 2D plain woven C/SiC composites were performed on Instron8801. Infrared (IR) thermography was recorded using an infrared camera. Acoustic emission (AE) signal was detected by two AE wide band sensors attached on specimen. They were measured synchronously and real-timely. Thermal dissipation Q was deduced based on the first law of thermodynamics. When the applied stress was lower than fatigue endurance limit, Q rose in the early cyclic loading stage and then the rate of Q accumulation gradually approached a steady value as the proceeding cycles, conversely, Q rose quickly until led to failure of the composites. AE accumulated energy was discussed based on the AE data. Higher applied stress would cause more damage within the composites, and more AE signals were detected. Compared with damage calculated from modulus, Q and AE accumulated energy had fairly well agreement with the damage. It can be concluded that it is possible to employ these non-destructive evaluation methods as in-situ damage evolution indicators for 2D C/SiC composites.