Gas foil bearings are a kind of aerodynamic bearings with good performance.However,due to its complex structure,the dynamic and static characteristics of the foil bearing are not easy to predict,and the calculation is also time-consuming.Since the widely used weak coupling method is computationally inefficient and time-consuming,a strong coupling method with high computational efficiency was developed based on the simultaneous principle.The pressure distribution was obtained by solving the Reynolds equation using the finite difference method.The bump foil was simplified as a spring model,the state equation of the foil bearing-rotor system was established with consideration of the film pressure,and the motion of the rotor and the deflection of the foil structure,and the simultaneous solution was carried out.Using this model,the dynamic characteristics of the foil bearing-rotor system was investigated by means of the rotor trajectory map and spectrum plot,concerning different parameters including the rotational speed,the rotor mass and the nominal clearance.The simulation results show that the stability of the system becomes worse with the increase of the rotational speed and the rotor mass.The system becomes unstable when the nominal clearance is too small.When the nominal clearance is large enough,the increase of the nominal clearance has little effect on the stability of the system.Compared with the traditional weak coupling method,the strong coupling method can further improve the calculation speed and accuracy,which provides a research tool for foil bearing design and performance prediction.