This paper explores the dynamic modeling and performance analysis of a wheeled-legged rover. The studied terrain-adaptive wheel-legged (TAWL) rover possesses 20 active joints and 4 passive springs. The end-effector of each leg exhibits 3R1T motion characteristics, along with an attached active wheel. For the dynamic modeling, the Newton–Euler formulation and the principle of virtual work are utilized to calculate the forces acting on each link and the torque of the driven joints. The dynamic model of each individual leg is first established. Then, the dynamic model of the whole body corresponding to different supporting and swinging legs is derived. For the performance analysis, the dynamic stability coefficient of the rover is determined. The stability coefficient around a certain supporting edge is defined as the ratio of the total moment exerted on that edge to the standard state’s total moment. The stability coefficient of the system is defined as the minimum coefficient value around all supporting edges. In order to verify the proposed modeling and analysis method, numerical simulations are conducted. The presented modeling approach can serve as the fundamentals for the optimization and control of the rover in future work.