After the end of the Cold War, the threat of "mixed war" has increased. Civil air defense projects and other types of urban security facilities are in urgent need of improving security protection methods, adding security inspection facilities, and preventing and controlling hostile terrorist attacks and rear sabotage. In wartime, civil air defense projects have far higher requirements for the efficiency of entrances and exits than subway facilities, and the space of the entrances and exits is limited, and the existing subway security inspection measures cannot be copied. Based on the analysis of prevention standards, security inspection procedures, technical means, etc., this paper proposes the use of new inspection techniques, combined with "classification inspection and character separation" inspection process innovation, which can set up personnel and articles under the limited space conditions of civil air defense projects. Each set of inspection equipment channels, within the economically acceptable range, not only meets the quality of screening but also ensures the efficiency of detection, so as to meet the requirements of civil air defense engineering cover and security inspection, and improve the measures to deal with the threat of "mixed war", which is the future of our country. The national defense forces provide more solid support.