Abstract: To study the active fault tolerant flight control,a modified robust multiple model adaptive control(RMMAC) methodology is presented.The mathematical models of both sensor and actuator faults are built firstly.Then the design procedure and features of the modified RMMAC method are introduced,and the proposed method is applied to the design of active fault tolerant flight control which integrates fault detection and control reconfiguration for a tailless aircraft.The simulation results show that the method can recognize the fault of actuators quickly and implements the reconfigurable control based on the probability computation of local controllers,so that the reliability,safety and survivability of the aircraft are improved.