Abstract: A novel parametric focusing algorithm, using the Cross Spectrum MUSIC (CSMUSIC) method, is presented to obtain a finely focused image of ground moving target on spaceborne distributed SAR. By exploiting the space-time property of the azimuth echo signal, an Extended Space-Time Model (ESTM) is firstly introduced. Then on the basis of this model, a parametric estimating method based on subspace theory is presented to estimate the azimuth velocity of moving target and to obtain an image of finely focused. The proposed method has higher precision and lower calculation burden than the conventional algorithms. The simulation results indicate that the proposed method is verified to be more efficient in contrast with the conventional algorithms.