according to the relation of analytic geometry between the required coverage of target and the coverage of air defense weapon, establish air defense weapons positions configuration model whose index is the best distance between the covered target and air defense weapon, covering curved surface’s projection in the ground. Basing on these models, according to the ratio between the projection area on ground of the cover surface under protection and the projection area on ground of the intercept surface, we can educe the fire control effectiveness of air defense weapon. The study can offer more visual and reasonable support for the commander on position disposition problem, and it can make the best possible use of the performance of air defense weapon.