Due to the capacity constraint on traffic flow in multi-aerodrome terminal airspace, an algorithm to allocate traffic flow according to capacity in multi-aerodrome terminal airspace is studied by exploring collaborative decision making and law of economics. First, considering factors such as airline’s gross income, operation cost and delay cost, a traffic optimization model to maximize total airline’s profit is established, and constraints including capacity of multi-aerodrome terminal airspace are imposed as well. Then, an improved genetic algorithm to obtain optimal solutions to the optimization model is developed. Traffic flow can be better allocated according to capacity in multi-aerodrome terminal airspace by using the proposed strategy, while airline’s profit is increased simultaneously.