In this paper, the dynamic properties of a spatial flexible beam with large overall motion and nonlinear deformation in non-inertial reference frame are investigated. The dynamic response of the present model is compared with those of zero-order approximate model and one-order coupling model. Then changing of dynamic stiffening terms due to the new coupling terms is discussed according to different models. At the same time, the effect of initial static deformation on the tip is considered to study the vibrant deformation of flexible beam. In addition, when the overall motion is free, the rigid-flexible coupling dynamic theory is extended to spatial structure from planar structure. The difference among zero-order approximate model, one-order coupling model and the present exact model is revealed by the frequency spectrum analysis method and concludes that the speed of overall motion is a vital cause for the difference among different models. And the dynamic stiffening phenomenon still exists in a rigid-flexible coupling system while the overall motion is free.