For resolving the problem that the CS algorithms couldn't compress SAR data in range direction using the original signal with errors
the author introduced an Equivalent-Squint Wavenumber Domain algorithm.In this paper
the Squint-Range-Model based wavenumber domain focusing algorithm for high resolution spaceborne SAR is derived from original response signal using Bamler's method in accordance with the equivalent squint range model.This algorithm is suitable for precise imaging of high resolution spaceborne SAR with large range cell migration.Simulated data of point scatterer response is used to demonstrate the effectiveness of this algorithm and the evaluated result is given.