Floating offshore wind turbine （FOWT） is the key structure for wind energy harvesting in deep sea area， and the dynamic response analysis of FOWTs under complex environmental conditions plays a significant role in guaranteeing the structural safety of the system. In the stage of preliminary design and scheme comparison， an efficient integrated dynamic analysis model is necessary to quantitatively capture the main dynamic characteristics of FOWTs. In this paper， a multi-rigid body fully coupled dynamic analysis model is established for the spar-type FOWT. Based on the Lagrangian equation， an 8-degree-of-freedom equation of motion of the spar-type FOWT considering the generator torque control and blade pitch control mechanisms are derived. According to the parameters of a 1∶50 scaled physical model of a spar-type FOWT， the scaled numerical analysis model is established by using the multi-rigid body dynamics model. On this basis， comparisons between the numerical and experimental results under static condi tions， wind only conditions， wave only conditions and combined wind and wave conditions are implemented. In addition， the numerical analysis model of the spar-type FOWT prototype in the OC3 project is also established by using the proposed multi-rigid body dynamical theory， and the comparison of the analysis results with FAST is carried out as well. By comparing with the experimental results and the numerical simulation results of FAST， the effectiveness of the proposed multi-rigid body dynamics model of FOWTs is thus verified. The fully coupled model proposed in this paper not only provides a basic for the preliminary design and scheme selection of spar-type FOWTs， but also provides a reference to the development of simplified integrated models for other types of FOWTs.