Acoustic emission monitoring could be a powerful technique for various forthcoming rock engineering projects, because it provides information on failure mechanism and possibly on fracture prediction of rock structures. The author has been engaged in researches and developments on the monitoring technique for more than ten years. In this paper, acoustic emission monitoring during hydraulic fracturing, heating fracturing and excavation of an underground powerhouse is reviewed, mainly based on works of the author. Through the reviewing, the applicability of the monitoring to rock engineering projects is also discussed.