In order to refine a rotor center's orbit,a novel refinement approach free from decomposition was proposed by using a harmonic window method.Based on researches for part decomposition in frequency domain.this method is capable of decomposing the arbitrary detail into the frequency section,then the interested frequency band could be extracted and reconstructed in the time domain,so the refinement of rotor center's orbit in one or more interested frequency bands could be realized.The advantage of the harmonic window method in rotor center's orbit refinement has been proved by the successful refinement of first seven frequency sections from the miniature rotor test-bed's vibration signals,This method also has a simple algorithm and is easy to be realized,which provides a new method for refinement of rotor center'orbit.