Image preprocessinghas assumed an essential part ofhandwriting recognition system. The main primary stage of the image preprocessing is thresholding.Aneffectivethresholdingmethodis based on Fuzzy C-Means clustering (FCM) for Arabic Handwriting Recognition system (AHR) has been proposed in this paper. Since thresholding stage in AHR isimperative to reduce the dimensionality of image to remove the undesirableinformation (noise)then increase the processing speed of the AHR system. The algorithm is performing by feedingthe intensity of the pixel value of the image pixels into the FCM clustering algorithm. Exploratory results with artificial and real life images show thatthe proposed method gives better accuracy and good efficiency than the current methods.