The invention discloses to a multiscale Retinex image sharpening algorithm based on bounded operation, relates to the technical field of digital image processing and solves the problems that existing image intensification algorithm has limitation in realizing image sharpening and generates a halo formation in a region with relatively strong change of intensity of illumination and the like. The algorithm comprises the following steps: according to a bounded generalized log ratio operating model put forward, replacing logarithm transformation in Retinex algorithm by addition in a GLR model to carrying out logarithm-like transformation on an image; separating high and low frequency information by adopting a self-adaptive guide filter kernel function of different scales to obtain illumination images of different scales; then removing illumination components by using subtraction of the GLR model to partition reflective components of different scales from an original image; fusing effective information of different scales by using multiplication and addition of the bounded GLR model for replacing conventional algorithm through a four-way Sobel gradient image to obtain a final multiscale reflective component image, namely the final sharpened image.