Abstract: The terrorists have considered the subway station as one of the primary goals of the attacks, because it always has a weak security system and relatively dense. A secondary triage-joint defense optimization model of the subway security screening in special period is put forword, based on optimizing subway security process and building joint-defense system. Results show that, in the special period, with the introduction of ID card information database and fingerprint-face recognition system (FFS), the passengers are diverted to green, orange, red channel to pass the security checks, This method can significantly improve the level of ordinary passengers social welfare. When the accuracy of the original X-ray detection system is lower, the social welfare of this system will be higher; Along with the higher proportion of the passengers diverted to the orange channel and the higher proportion of potential attackers in the orange channel, the social welfare of this system will be larger, and the probability of violent terrorism event will be smaller; When the recognition rate of recorded fugitives is higher, the greater social welfare can be gotten. The positive feedback of the joint-defense system can also stimulate the security department to optimize the identification system, until the system reaches the optimal state with the zero marginal social welfare.

Key words: secondary triage-joint defense model, terrorism, subway security screening, multisectoral joint defense