In this paper, a sort of aliasing degree pre-estimated MAP (maximum a posteriori) algorithm, PEMAP, is proposed. It is used in super-resolution processing of satellite images on the ground. The aliasing degree of satellite images is firstly determined in frequency domain by spectrum analysis, and then used in a joint estimation of the registration parameters and high-resolution image in space domain as a priori information. This algorithm overcomes the blindness and instability of the MAP algorithm and improve its flexibility. Good results have been shown in a practical satellite image processing.