The invention discloses a grayscale normalization method of fingerprint images, which aims at solving the technical problem of blocking effect and has the characteristics of fast operation and good real time. The technical scheme is as follows: carrying out non-overlapping blocking on the images, computing the grayscale histogram statistical characteristics of a block which coincides with the center of the current block and is larger than the current block, carrying out grayscale normalization by utilizing grayscale histogram equalization and grayscale stretching, after processing one image block, adopting an incremental method to compute the grayscale histogram statistical characteristics of the image block when the next adjacent image block is processed and finally covering the originalimage with the grayscale normalization result. Being adopted, the method of the invention overcomes the problem of blocking effect, features high speed, has better real time and can be better used for real-time embedded systems.