Abstract:To measure the sub-pixel image motion which is caused by satellite attitude instability or vibration，the joint transform correlator method is designed. The mathematics principles were clarified, the position of matrix CCD on the focal plane and the method of getting input image were presented. Sub-pixel image motion input image which to be tested was got by linear interpolation and pixel combination. The results show that the error does not change with different scene of input images, and the error RMS of 0.2 has been achieved.