Abstract: Coupling-Optimization Algorithm is comprised of coupling methods used in SPEY aeroengines and optimization method.This new method can be used to simulate the engine performance accurately on the basis of very limited engine test results even if its component characteristics are unknown.In addition,the component characteristics can also be inferred in the same time.This method has been used to simulate the performance of a turbofan engine and to infer its unknown component characteristics.The comparison of the results with the engine test data confirms the feasibility of the proposed method.