Abstract: In order to alleviate the data collection and transmission burden of the sparse target scene echoes for master-slave mode of formation-flying satellites SAR, a kind of echoes sparse method for formation-flying satellites SAR is proposed. On the basis of analyzing the properties of formation-flying satellites SAR echoes, sparse matrices, measurement matrices and compressive sensing matrices of the master-slave mode are established. The sparse matrix in range is constructed by using the range model between target distance cell and the equivalent phase center of formation-flying satellites. The sparse matrix in azimuth is based on the phase model of each azimuth sample data. The measurement matrices in range and azimuth are employing the method of analog-information-conversion measurement framework and random demodulation, respectively. According to the data transmission characteristics of the master-slave mode of formation-flying satellites SAR, the compressive sensing imaging method for the master-slave mode with low data transmission payload is proposed, and the high-quality image of formation-flying satellites SAR is obtained by reconstructing the sparse echoes using the orthogonal matching pursuit algorithm. The simulation results show that the proposed method can reconstruct the original sparse target scene with less echoes. Thus, the formation-flying satellites SAR imaging based on low data transmission payload can be realized.