Abstract: The dynamic model for analyzing the coupled load of satellite with the launch vehicle is condensed from the satellite’s unreduced finite element model by the component mode synthesis method. With the current condensation method, the condensation is only made once, thus all the finite element models of the satellite sub-structures are required to be unreduced, including the antennas, the solar arrays, and other parts. While sometimes the physical model of the satellite is not available from the manufacturers for the sake of the technical security, which brings about difficulties in implementing the " one-time condensation method”. This paper, in view of this limitation, proposes a method to achieve a second-time condensed dynamic model of a spacecraft when the initial model is composed of unreduced finite element sub-structures and reduced ones. Finally, the satellite/launch vehicle coupled load analysis is carried out jointly with the manufacturer of the launch vehicle, with a desirable result to prove the effectiveness of the method.