Performance-related critical technologies and difficulties in the development of engines with a thrust to weight ratio up to the level of 15 are considered.For typical flight roles

the selection of optimum cycle parameters of augmented turbofan engines based on integrated analysis is discussed.As thrust vectoring nozzle is the feature of advanced fighters

the difficulties in implementing thrust vectoring are summarized.The reduction of development cost and time consumed for development is very imporant.Numerical propulsion system simulation is one of the effective ways for engine design and development

as well as cost and time saving and must be the center of our attention.Engine condition monitoring and fault diagnosis may enhance engine operating safety and reduce direct operating cost

so that the development trend and key techniques of fault diagnosis are also surveyed.In conclusion some important tasks are presented.