In the missile-borne SINS/SAR integrated navigation system, there exists the issue that the imaging quality is influenced by distance migration of missile maneuver ability. The paper gives a novel Burg-Chirp Scaling-Dechirp image algorithm. It structures the improved phase compensation factor to compensate the influence caused by range migration. Besides, take Dechirp technology on the part of aperture data in azimuth focus processing to optimize algorithm structure. Meanwhile, by way of establishing the regression model, the two dimensional spectrum of the image is extrapolated, which makes up for the shortage of the limited spatial resolution of the classical CS algorithm. With the compared simulation of the new algorithm and the classical CS algorithm, it shows that the new imaging algorithm can effectively improve the image quality of the point target and get the real-time high resolution SAR image.