The Enhanced Flight Vision System(EFVS)is a complex airborne electronic system,for which the conventional fault analysis is complex and error prone.On this basis,the concept of formal modeling is introduced and a formal modeling method of a EFVS based on fault coupling model is proposed.The fault propagation mode of the system is determined via functional interaction model of the EFVS.The system architecture and data flow are abstracted,and the fault coupling formal model is established hierarchically.The model checking tool is introduced to verify the system model,and automatic operation is carried out in combination with typical system fault states,so as to obtain the minimal cut set of the fault tree in fault state.The results show that the method is highly automated,which is helpful to improve the efficiency of the fault analysis process of enhanced flight vision system.