Abstract: Based on the working principle of the satellite borne scanning imaging system, we expound traditional line scan and oversampling detection. The mathematical modeling and simulation imaging of the point target detection in two detection modes are presented. The oversampling system oversamples the image twice along the line direction while 2 to 10 times along the scanning direction(i.e. the time direction) with Matlab. The signal is analyzed by routinely scanning and oversampling the spot targets. The relationship between the power of the signal and the sizes, and the imaging effects brought by different locations of targets are given. At last, we obtain 4X oversampling images of different targets through two channels and analyze the multi-pixel phenomenon existing in the images.