Abstract：The microfractures in a brittle material like rock may appear or grow while loading. Microfracturing process in a material results in energy dissipation and acoustic emission(AE). Acoustic emission is a good tool to detect the damage in brittle materials. Because it can monitor the microfractures in the body continuously and in-real-time and is better than other methods. Large-scaled gneiss failure experiments under triaxial loading are conducted. The size of the specimen reaches 1.05 m. In order to simulate the effect of tide-generating force of the sun and the moon，a cycle stress is loaded superposing on a basic axial load level. Lots of acoustic emission during the entire loading are recorded. The recording is able to indicate the occurrence time，location and magnitude of every damage (micro-crack) in the specimen. Acoustic emission record is used to study the two macroscopic failure precursors of rock，accelerating energy release (AER) and load/unload response ratio (LURR)，which can be served as the experimental foundation of earthquake prediction. At the same time the Felicity effect is identified in the experiment.
