Abstract: The reason of photo response non-uniformity (PRNU) of image sensor's photo response was analyzed in this paper at first. It was concluded in two faces, one caused by spatial noise which based on materials, manufacture crafts and offset and another caused by temporal noise which based on its response with time drift, theses two factors influence the PRNU of image sensor's photo response gravely. To describe the affection of spatial noise and temporal noise, the model of sensor based on the hypothesis that linear of image sensor's photo response was made, and the erase non-uniformity of CCD by Least Square Methods based on this model was proposed. Experiment results show that the proposed algorithm is effective to the correction of image sensor's PRNU.