In order to provide quick and correct fault positioning strategy for the software design of in situ fault position indicator of missile launching and control system, analysis of elements and working principles of the missile launching and control system was made. Taking the missile launching and control system as the research object, a FTA method was used to build fault tree, and qualitative and quantitative analysis was made for it, minimum mow was calculated to gather importance, the main fault mode, the fault reason and the initiative period of fault position were confirmed and this lays theoretical and practice foundation for the quick and accurate fault positioning.