Domestic transport category airplanes have been developed successfully and gradually put into use. In order to maintain the continued airworthiness of domestic aircraft, the role of root cause analysis (RCA) in incident investigation is emphasized. Standardization of RCA procedure and methods will help to improve design and safety of domestic transport category airplane. Through the research of RCA procedure and methods of continued airworthiness event used in Europe and the United States, a structured RCA tool is used to carry out a typical accident and it is suggested that relevant departments should optimize RCA procedure and methods for domestic transport category airplanes and develop RCA assistance software as soon as possible.