An Air Turbo Rocket (ATR) engine is an air breathing propulsion system that integrates turbojet,ramjet and rocket in a single unit.Since it was brought to attention of U.S.Army in 1980s for its potential advantages of broad velocity field,simple structure and high specific impulse,extensive studies on ATR such as numerical simulation,ground tests and flight experiments have been conducted in America and Japan and variety of meaningful results have been gained.