ETOPS is an operational requirement put forward by the International Civil Aviation Organization (ICAO) in order to ensure the safe flight of civil aviation aircraft, which is widely used in intercontinental routes, especially cross ocean flight. The core of ETOPS type design approval is the airworthiness certification of ETOPS significant systems. ETOPS significant systems airworthiness certification is studied. The airworthiness requirement that refers to ETOPS significant systems is analyzed. The Methods of determining and verifying ETOPS significant systems are proposed. The approval requirement for time-limited ETOPS significant systems are analyzed. The determination method and verification method of ETOPS significant systems proposed in this paper have been applied in engineering practice, and substantive progress has been made. It has proved that the research of this paper can provide guidance for civil aircraft ETOPS type design and airworthiness certification.