Due to the skew Region Of Support (ROS) of the two-dimensional wavenumber domain for high squint SAR data, conventional Omega-K algorithm can not exploit the ROS efficiently enough and degrades the resolution when choosing the square region to process. So a modified Omega-K algorithm is proposed in this paper to deal with the high squint SAR data for sub-aperture imaging. The maximum usage of ROS is obtained by the coordinate axis rotation. For the following azimuth dependence, the method of azimuth resampling is adopted to realize the uniform focusing. Compared with the traditional Omega-K method, the modified Omega-K algorithm is focused in azimuth wavenumber-domain because of the limitation of the azimuth sub-aperture ROS in order to avoid zero padding operation, and increase efficiency. Simulation results and raw data processing validate the effectiveness of the proposed algorithm.%斜视SAR数据两维波数域支撑区具有斜拉特性，并且斜视角越大，斜拉越明显；在大斜视成像时，常规Omega-K成像直接选取矩形支撑区进行处理，支撑区利用率低，难以满足成像分辨率要求。针对子孔径大斜视SAR数据成像，该文提出一种基于方位谱重采样的改进Omega-K算法。该算法通过坐标轴旋转，实现波数谱支撑区利用率的最大化，针对伴随的方位空变问题，采用方位谱重采样方法校正空变性，实现方位统一聚焦。另外，由于对于子孔径数据处理，考虑位置支撑区受限，不同于传统Omega-K方法，改进Omega-K算法在方位波数域成像，避免了位置域成像需要的大量补零操作，提高了处理效率。点目标数据仿真和实测数据处理验证了该文算法的有效性与实用性。
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