Frequency-Modulated Continuous-Wave Synthetic Aperture Radar (FMCW SAR) is a promising compact remote imaging sensor. In this paper, a ground moving targets refocusing method is presented to provide FMCW SAR system with simultaneous moving targets indication application. This method is modified from range migration algorithm. To discriminate the target optimally, the concept of relative motion is utilized. The moving target is refocused like a fixed target. Its migrations both in the range and azimuth directions are completely compensated. Blind hypotheses of the relative velocities are used in the detection phase of moving targets. The step size between the hypotheses involves a trade-off between the computation load and detectability. In this paper, we determine the discretization based on the principle of stationary phase. The discretization reduces the computation burden and secures the detectability.