Being bui1t up , the mathematlcs model of the plant is always influenced by the parameters uncertainties. Whatever control theory used for the integrated flight/propulsion control , it is necessary to be sure that the flight/propulsion closed loop control system has the strong robust stability. This paper applies the H∞ theory to the flight/propulsion control system. The followmg questions can be covered in this paper: the quadratically stability concept mentioned in the flight/propulsion control; H∞ controller for flight/propulsion control designed; digitally slmulation of the flight/propulsion control closed loop system; the satisfied conclusion to prove the system meets the robust requuements of the flight/propulsion control system.