Abstract: In this paper, a refined Secondary Range Compression (SRC) imaging algorithm for large squint air-borne Synthetic Aperture Radar (SAR) is presented. Based on the squint range mode, refined SRC algorithm for squint mode SAR is deduced directly. By compensating the cubic phase term of range frequency, the problem of range compressing unsymmetrical sidelobe is improved effectively, By compensating the parallel phase term introduced by forward looking beam, the shift of image location in azimuth is solved. Implemented steps and algorithm flow are given, imaging effects are compared in different squint angle as well. The simulation demonstrates that imaging quality is improved obviously and this algorithm is suitable for large squint air-borne SAR imaging.