Taxiing route optimization of departures at airport surface is a hot research in the field of civil aviation. Against the problem that the existing optimization algorithms which study only from the perspective of shortest path or minimum taxiing time of departures ignoring the impact of airline satisfaction and taxiway load rate to the taxiway scheduling, a taxiing route optimization algorithm for departures based on backpressure routing is proposed in this paper. Firstly, the optimization problem is equivalent into the routing problem in network topology. Then the taxiing route which possesses the maximum airline satisfaction and minimum taxiway load rate is obtained by introducing the backpressure routing algorithm. The simulation results of a domestic hub airport runway and taxiway system show that the taxiing route achieved by this algorithm ensures the utility of the runway and taxiway while reduces taxiing time of aircraft effectively, improving the throughput of airport simultaneously.