The development plan and performance evolution of turbo shaft engine in the United States since 1970s are reviewed. The selection of different cycle types and cycle parameters is analyzed. Performance statistics analysis is carried out. The foundation and the method of helicopter/engine integrated design theory are introduced. At last, this paper proposes the concept of the new generation super low emission turbo shaft engine, and points out that reducing total oil consumption and increasing the power to weight ratio are the two key methods in the design of super low emission.