Abstract: Optimization methods to control the in-flight shutdown rate and the maintenance cost of civil aero-engines are presented in this paper. The mathematical planing approach to determine the optimal in-flight shutdown rate of an aero-engine is developed, in which the lost expectation of in-flight shutdown is taken as the index of indirect operating cost and the minimum sum of maintenance cost and indirect operating cost is treated as the optimization objective. On the basis of the mathematical planing, a simple optimization method to control in-flight shutdown rate and maintenance cost is provided. The methodologies have reference value for an airline company to make decisions to control task reliability level and maintenance cost of an aero-engine in the wing.