Abstract: The amplitude modulation of rotating scatter centers on radar echo is investigated. Based on the above, a method of extracting space characteristics of rotating scatter centers through micromotion is proposed. At first, the spectra of echoes can be gained through temporalfrequency analysis. Then based on the microDoppler frequency difference, the scatter energy of each scatter center can be estimated through edge characteristics of spectra, which varies with time. Combined with estimating of micromotion parameters, the space characteristics of rotating scatter centers are extracted, which is validated by simulation and outdoor radar test. The space characteristics of rotating scatter centers can tell the structure information of rotating parts and improve the performance of target recognization.