A new mathematic model for analyzing and calculating the degree being covered reciprocally between components of aeroplane was proposed. With it we can analyze that whether a fraction of missile warhead impacts the vital component of aeroplane directly through crust of aeroplane, and cannot be held up midway by other components. The method is very simple, just like judging whether something is covered by sighting, on a condition, that the surface of components of aeroplane must be divided into a lot of little pieces. It is suitable for analyzing and calculating the degree being covered reciprocally between complex components with computer specially. Through simulation calculating, the validity and the feasibility of the new model were validated. It can be applied to study airplane's viability when being hit, to optimize airplane's design, to study the cooperation degree between fuze and warhead of missile, to optimize the parameters of fuze and warhead.