In response to the air and space threats in the new era, the coverage of the air defense and anti-missile early warning equipment is deduced. Firstly, analyzes the characteristics of the aerospace threat target and its challenges to the early warning detection system. Then in a setting of deductive needs of air defense and anti-missile early warning equipment coverage ability, define 2 main evaluation indicators, regional coverage and multiple coverage ratios, establish their calculation methods. Then take the US air defense and anti-missile system as a typical case, analyze its equipment coverage capability and the equipment deployment features are summarized. The results show that the study is effective and feasible, and can provide timely and reliable information for missile defense system.