Abstract: In synthetic aperture localization, the squint mode is more flexible compared to the broadside mode, and can better adapt to target localization in complex environments. However, the Doppler center frequency is no longer zero in squint mode, resulting in azimuth localization errors for the target. To address this issue, a passive localization algorithm based on squint synthetic aperture is proposed in this paper. First, the algorithm constructs a squint positioning model in full aperture mode, which compensates for the Doppler center through linear phase modulation and effectively corrects the frequency offset of the Doppler center, thereby eliminating positioning deviations. Then, azimuth-focusing is achieved through matched filtering to obtain focused image of the target. Finally, geometric correction is employed to eliminate the spatial variability of azimuth bias, thereby achieving accurate localization results. Simulation analysis and Monte Carlo experiment results demonstrate that the proposed algorithm can effectively enhance localization accuracy under low signal-to-noise ratio. Experimental data further validate the effectiveness and correctness of the proposed algorithm.