Abstract: In order to mitigate flight delays caused by airport capacity limitation, a novel arrival-departure capacity model was built with the maximum flow as the objective. In this model, a discrete-time mixed queuing algorithm is employed to form the transition probability matrix for potential conflicts, and a conflict factor is adopted to adjust the transition probability matrix for optimization of model performance. The mathematic formula for arrival-departure capacity is then derived, and calculation procedures of the capacity algorithm are designed. A simulation was conducted using the actual data collected from Chengdu Shuangliu international airport. The results show that the standard deviation between the calculated number of flights and the actual data are 1.552 and 1.436, respectively, when the arrival and departure rates of flights are 0.6 and 0.5, and the throughput rate of airport (TRA) is 0.8. When the arrival requests obey Poisson distribution, the number of rejected requests decreases with an increase in TRA, and the relationship between arrival capacity and TRA shows a positive correlation trend.