Abstract: In SAR imaging, Range Migration Algorithm (RMA) can be implemented effectively under the condition of the big area and low frequency, especially in UWB-SAR imaging. However, RMA must include the so-called stolt interpolation, which will cause the huge amount of calculation. In this paper, NUFFT will be applied in RMA, and our approach consists in substituting both the stolt interpolation and the final range inverse FFT by a single NUFFT, wipe off skillfully vast calculation arised from stolt interpolation. Numerical simulations illustrate the performance of the new method.