Abstract: In order to improve the efficiency of airport security screening,queuing theory and probability theory,combined with the speed and accuracy operating characteristic curve,were used to build a mathematical model for the two-stage security check system.On the basis of analyzing some date on actual examples,effects of both the speed of first-stage screening and the proportion of sampling on the first stage,the second stage and the entire two-stage security system's false clear rates,false alarm rates and average wait time for passengers carry-on items studied.The results show that when the arrival rate is unchanged,the longer the maximum detection time in the first stage,the higher both the false clear rate and the false alarm rate of the entire two-stage security check system will be,and the shorter the average waiting time for passengers carry-on items,that when the maximum detection time in the first stage exceeds 5 seconds,its effect on the average waiting time will be minimal,and that increasing the proportion of sampling will increase both the average waiting time and the false alarm rate of the entire security check system.

Key words: two-stage security check system, false clear rate, false alarm rate, probability model, operating characteristic curve, screening time