Aiming at the large computation of the maximum fuzzy entropy thresholding method, a fast algorithm for the maximum fuzzy entropy thresholding method is presented. It is based on the analysis of the character of the S-type function and the properties of the fuzzy entropy. The fast algorithm reduces the time complexity from O(L⁴) to O(L³). Meanwhile, the fast algorithm avoids the defaults of reaching the local extrema by the optimization methods. Therefore, the fast algorithm raises the speed and maintains the segmentation performance of the maximum fuzzy entropy thresholding method.