In order to improve the Mura defect of the liquid crystal display, a grayscale compensation was proposed. Based on the brightness distribution matrix of typical grayscales, bilinear interpolation and the most value filtering was used to filter image, and then calculate the target brightness of the full screen. According to the fitted curve of grayscales and brightness, the compensation data of grayscales was obtained. The results of the experiments which performed on a 55-inch liquid crystal display module show that Mura stripes of the images diplayed on the module disappeared, and the Mura indexes decreased by Mura compensation.It has little influence on the overall brightness and contrast of displayed image.