Aimed at the image registration problem in interferometric inverse synthetic aperture radar (InISAR), the causation of the offset between two ISAR images for different interferometric antennas along one baseline was analyzed. Then a quantitative analysis of the offset and its influence on the following interferometric processing was discussed. It was shown that the sub-pixel offset in the down-range direction and the pixel offset in the Doppler (cross-range) direction induced mismatching of two ISAR images. A novel image registration method based on phase correction was proposed to solve the mismatching problem in InISAR imaging. Simulation results demonstrate that the offset between two ISAR images is compensated effectively when the proposed new method is used, achieving an improvement of the quality of three-dimensional (3-D) image consequently.