The inflatable spinning structures have many applications in aerospace engineering， the dynamic characteristics of which have a significant impact on the space missions. In this paper， therefore， an accurate dynamic model and the corresponding dynamic characteristic analysis of an inflatable spinning structure are studied. The dynamic models of the flexible inflatable tube and the rigid satellites are established by using the reduced shell element of absolute nodal coordinate formulation （ANCF） and the natural coordinate formulation （NCF）， respectively. By using the Lagrange multiplier method， the kinematic constraints are introduced into the system dynamics equations so that a flexible multibody system dynamic model is obtained. Under the assumption of linear vibration of the inflatable spinning structure at the equilibrium configuration， the eigenvalue equation of the inflatable spinning structure is derived by coordinate transformation. The eigenfrequencies and the corresponding modal shapes of the inflatable spinning structure are computed via a frequency shift， and verified with the results from the finite element software. The influence of the spinning speed and inflatable pressure on the eigenfrequencies of the inflatable spinning structure is studied. The results reveal that the spinning speed and inflatable pressure can give rise to the phenomena of eigenfrequency veering， crossing， and switching， which will affect the stability of inflatable spinning structure.