1.08d。Computed tomography（CT） images and histograms scanned of Fushi apples in different storage time were compared and analyzed. It’s found that the images were getting brighter with the storage time increased and the right peaks of the histogram were moving right. The average gray value of the CT images was calculate to design a simple and fast image processing algorithm. The linear relationship was established between the average gray value and the storage time. The prediction error of the model was low and the average prediction error was 1.08d. 