In this paper, a new algorithm is presented to image ground moving targets and estimate their motion parameters in a synthetic aperture radar system based on improved axis rotation-time reversal transform (IAR-TRT). In this algorithm, the second-order Keystone transform) is applied to correct the range curvature, where the Doppler ambiguity caused by a fast-moving target is considered. Then, residual linear range migration and Doppler frequency migration are eliminated by IAR-TRT, which performs an improved axis rotation transform to correct the range walk and subsequently realizes the coherent integration based on time reversal transform. Finally, a ground moving target is well focused. Additionally, the proposed method has a relatively low computational complexity since the exhaustive searching for Doppler chirp rate estimation is avoided. The effectiveness of the proposed algorithm is validated by both simulated and real data.