Solar Array Drive Assembly(SADA) is a core component of high-power and long-life satellites, and the shafting is an important part of SADA. Its vibration characteristics analysis is very important in structural design and dynamic analysis. The paper theoretically derived and calculated the natural frequency of the shaft system under the action of bearing preload and span, and established a corresponding finite element simulation model in ANSYS. It is concluded that the natural frequency of the shafting increases with the increase of the bearing preload and the span, and the influence of the bearing span is more significant.