Considering the actual during a flight operation that flight flow and airport capacity has dynamic feature, the concept of sliding time window has been used in airport flight flow optimization allocation problem, and puts forward a method of dynamic optimization allocation of airport flow based on sliding time window. The principle of optimization allocation of airport flow based on sliding time window is discussed in this paper, this method use ongoing dynamic optimization allocation instead of static one-time optimization allocation to get optimal flow allocation scheme of current time period in real time, this method could provide decision support for tactic airport flow management. The experimental results shows this method could achieve real time optimization allocation purpose well in dynamic environment, while static method of optimization allocation could not be used in dynamic environment, verified the feasibility and efficiency of this method.