Abstract: The wavenumber domain algorithm (ur-k algorithm for short) has the ability to process wide-beam SAR data because it has the ability to handle the range-azimuth coupling correctly. However, because the traditional nj-k algorithm can not integrate with the motion compensation approach, it sometimes results in bad image. Some improvement of the traditional ra-k algorithm is presented in this paper, that is, the deconvolution is used to separate the range migration correction from the azimuth compression, and then the sub-aperture and autofocus approach are applied to the ro-k algorithm, which makes the improved nj-k algorithm more practicable. At the end of this paper, a set of P-band wide-beam SAR data is processed by the improved tn-k algorithm, and the resultant image quality is obviously increased.