By analyzing the basic elements of air traffic impedance and referring to the road traffic BPR impedance function, an air traffic impedance function model is proposed. This model study the air traffic impedance problem considering the runway saturation of departure and landing airports, which provides a new research idea for air traffic impedance analysis. The flight data of ZSNJ-ZBAA are used for fitting analysis and model parameters calibration. The results of the model only considering the runway saturation of landing airport are presented separately according to the traffic control situation. Furthermore, the parametric tests are conducted, the fitting performance are compared with the model considering the runway saturation of landing airport in terms of its goodness-of-fit index. Comparison shows that the accuracy of the integrated model is improved by 11.9% without flow control and 16.7% with flow control, which can provide a reference for air traffic management.