The geometric accuracy of digitally mosaicked TM image is analyzed in this paper. There are some defects to maintain geometric accuracy of the mosaicked TM image by control points selection. The geometric error of the mosaicked image is aboat 8 pixels. The rotating method is easy to use for registering TM image

meanwhile it keeps the geometric accuracy of the mosaicked TM image. The geometric error of the mosaicked image by rotating method is less than 2 pixels.