The invention discloses a bunching SAR clutter suppression and moving target refocusing method based on an approximate observation matrix, and the method comprises the following steps: 1, building a geometric model of SAR data collection, and obtaining an echo signal; 2, performing PFA imaging processing on the mixed signal, estimating motion parameters of the moving target by adopting an FRFT algorithm, and constructing a dictionary of a radar projection matrix of the moving target; 3, constructing a joint projection matrix of the static target and the moving target to obtain an approximate observation matrix for clutter suppression and moving target separation; and 4, constructing an iterative shrinkage threshold algorithm based on the approximate observation matrix to obtain a clutter suppressed and focused moving target image. According to the invention, clutter suppression and moving target refocusing are realized by using the joint projection matrix of the moving and static targets, and a radar projection matrix and data are prevented from being stacked into a column vector by using an approximate observation matrix method, so that the calculation complexity and the storage memory are reduced.