Abstract: Micro-motion feature is one of the effective features used for radar target recognition in the middle section of the ballistic curve. The micro-Doppler expressions of the scattering center at the conical point and two sliding scattering centers in the conical bottom are derived, firstly. The micro-Doppler of the scattering center at the conical point calculated by its micro-Doppler expression is little different to that which is getting by the Geometrical Theory of Diffraction (GTD). The other two scattering centers micro-Doppler achieved by the two methods coincide with each other. Three correlations of the micro-Doppler of the three scattering centers are founded by analyzing their micro-Doppler expressions. Then a method of precession and structural parameter estimation is proposed by using the magnitudes of the micro-Doppler at some times，which can obtain from the time-frequency analysis. Using the method to extract six precession and structural parameters in different angles of incidence is analyzed, and the simulated results validate the effectiveness of the proposed method.