Abstract: An analytical method about the “ground resonance” is introduced.It is applicable to the test stand of the rotor/fuselage combined model.A conclusion of the “ground resonance” is also presented in the paper.In order to meet the stability requirements about the "ground resonance" of the test stand,changes of the structure in the stage should be made according to different working circumstances.Thus dynamic characteristics of the testing stage can be changed to match the rotor model.This method can successfully solve the dynamic stability problem when a certain rotor model is running on the testing stage,which is discussed in detail in the paper.