Abstract: As an important power generation device of on-orbit spacecraft, the solar arrays need to rotate continuously under the driving of the solar array drive assembly (SADA) to achieve the goal of sun-pointing. On the other hand, the solar arrays are flexible appendages, so their flexible vibration is coupled with the position and attitude motion of the rigid hub and the rotation of the solar arrays, which will deteriorate the stability and control precision of the spacecraft. For this rigid-flexible coupled multi-body dynamics system, this paper, taking into account the structural characteristics of SADA, proposes a fully-coupled dynamics modeling method. This method remains effective for both single-axis and dual-axis SADA, and is applicable to the case of arbitrary number and installation orientation of solar arrays. It only requires appropriate adjustments to certain terms in the established dynamics equations. Based on the momentum theorem and the moment of momentum theorem of multi-particle system for moving point, with the mass center of rigid hub being taken as the reference point, the position and attitude motion equations are established, respectively; with the connection point between solar array and rigid hub being taken as the reference point, the rotation control equation of the solar array relative to the rigid hub is established. Furthermore, through coordinate transformation, the rotation control equation is projected onto the driving axes of SADA, and the more practical driving dynamics equation of SADA is obtained. The flexible vibration equation of the solar array is also established, and to simplify the model and make it more suitable for serving actual problems, the flexible vibration equation is decoupled from the other three equations by mathematics transform. Finally, based on the proposed modeling method, the mathematical models are established for the spacecraft with one single-axis array, one dual-axis array and two dual-axis arrays, respectively. The comparison simulations between these three models and professional dynamics software are carried out, which validates the effectiveness of this modeling method.