Abstract The performance of Space-Based Radar (SBR) to detect air or ground moving targets is influenced by earth clutter, so an effective algorithm to suppressing clutter can be designed if knowing the power and distribution of earth clutter. In this paper, the clutter model of SBR is deduced. Besides, the earth's rotation effect is taken into account and the modification to Doppler frequency is derived. Finally, we plot clutter space-time spectrum and clutter angle-Doppler traces based on the modeling. It is shown that earth's rotation together with Doppler ambiguity significantly degrade the clutter suppression performance of adaptive processing algorithms. Detailed derivations of these results are presented in this paper.