The purpose of the vibration test of spacecrafts is to assess their adaptability to low-frequency vibration environment during lift-off.This paper gives the simulation of the satellite ground vibration test(GVT) and the state of the satellite along with rocket during lift-off.The simulation results of these two states are compared on condition that the lateral vibration of satellite/launching vehicle(S/LV) interface is the same.It is shown that the dynamic responses of satellite vertex are totally different.This is because there is angular motion of S/LV interface during lift-off,but in the GVT,the angular motion is restrained.By means of numerical simulation of the lift-off state,the angular motion related to the translation motion of S/LV interface can be determined.Then,using this angular motion as supplementary condition to simulate the vibration test,the calculated dynamic responses of satellite vertex are identical with the lift-off state.It demonstrates that supplementing angular motion condition is an effective method to improve spacecraft ground vibration test more identically with the real lift-off environment.Furthermore,it is useful for the application of the multi-degree-of-freedom shaking table,and provides the basis for test condition requirement. The purpose of the vibration test of spacecrafts is to assess their adaptability to low-frequency vibration environment during lift-off. This paper gives the simulation of the satellite ground vibration test (GVT) and the state of the satellite along with rocket during lift- off the simulation results of these two states are compared on condition that the lateral vibration of satellite / launching vehicle (S / LV) interface is the same. It shows that the dynamic responses of satellite vertex are totally different. This is because there is angular motion of S / LV interface during lift-off, but in the GVT, the angular motion is restrained.By means of numerical simulation of the lift-off state, the angular motion related to the translation motion of S / LV interface can be determined.Then, using this angular motion as supplementary condition to simulate the vibration test, the calculated dynamic responses of satellite vertex are identical with the lift-off state. r motion condition is an effective method to improve spacecraft ground vibration test more identically with the real lift-off environment. Futuremore, it is useful for the application of the multi-degree-of-freedom shaking table, and provides the basis for test condition requirement