In fingerprint image pre-processing，fingerprint image binarization processing is a key step in a direct impact on the quality of fingerprint image thinning and accuracy of the extraction of the minutiaes. After an in-depth analysis of information entropy of fingerprint images, information entropy is introduced to the fingerprint image binarization algorithm. Through calculating a maximum entropy of the corresponding the region in fingerprint image, binarization threshold is estimated, and based on the achievement of this threshold fingerprint image binarization processing is done. The experimental results show that the algorithm is robust to noise and able to effectively realize the fingerprint image binarization.