Abstract: The influence on low-frequency spaceborne synthetic aperture radar (SAR) azimuthal resolution was analyzed, which was caused by ionospheric scintillation effects. The simulation results based on the phase screen theory indicated that the resolution got worse as the scintillation strength increase, while in strong scintillation conditions, the azimuth resolution declined seriously, even could not image. A new method called minimum entropy was introduced to correct the ionospheric scintillation error added to a picture of phased array L-band synthetic aperture radar(PALSAR) image, the simulation results proved that the minimum entropy method could correct the ionospheric scintillation effects effectively, and the azimuthal resolution got well recovered, closed to the original image azimuthal resolution, then the quality of the image was improved significantly.