Abstract: Contact fatigue was major failure mode for important rotating components bearing long term alternating load such as gears, bearings. It was very significant to monitor failure process of contact fatigue, detect damage degree, and reveal failure mechanism by acoustic emission technology. With the development of acoustic emission technology and discovery of signal processing technology, the research of contact fatigue failure detection was more indepth. This paper reviewed the development status about acoustic emission technique, summarized the research progress and existing problems of the application of acoustic emission technique to contact fatigue failure detection of bulk and coating components, and discussed the future research direction and thinking of solving problems at last.