This paper first gives a brief review about the three phases of the research of flexible multi-body system dynamics.Then in order to solve the deficiency in the traditional zero-order approach coupling model,a new modeling theory is proposed,and the discretizing method and experiment about "dynamics stiffening" problem and rigid-flexible coupling dynamics problem are investigated based on the new one-order approach coupling model.A set of experiment platform used for the theoretical study and the discovery of dynamic phenomenon is designed and built.Some research results are introduced.Some research targets are given at the end of this paper.