Aimed at the problem that the existing micromotion feature extraction method is unapplicable under the condition of the scattering coefficient of the complex timevarying, this paper puts forward a kind of micromotion feature extraction method based on timevarying 3D image coordinate reconstruction. By the use of this method, firstly, the micromotion signal model of the rotating symmetric space cone target is established, then the scattering points are separated by dynamic programming to obtain the timevarying threedimensional image of the target after the phase interference of each scattering point. And finally, the 3D micromotion feature of the target is extracted by using highprecision 3D coordinate reconstruction. The simulation results show that the accuracy of the proposed method is better than that of the traditional method. The proposed method can be well applied to the case of complex timevarying scattering coefficients.