In recent years, many applications in precision engineering require a careful isolation of the instrument from the vibration sources by adopting active vibration isolation system to achieve a very low remaining vibration level especially for the very low frequency under 10 Hz vibration signals. In this paper, based on our previous research experiences in the systematical modeling and study of parallel robots, a hybrid robot is described and the vibration model is given by using Lagrange's Equations. Then a dynamic analysis by using Kane's method is presented to verify the result. Finally, numerical simulations on the dynamic characteristics and natural frequency are presented.