The traditional histogram equalization is unable to preserve the input image brightness,when the contrast of an image is enhanced. Based on a Partially Overlapped Sub-block Histogram Equalization algorithm (POSHE),the recursive separateness method is used in the process of sub-block histogram equalization. A brightness preservation partially overlapped local histogram equalization algorithm which can preserve the brightness is proposed. The sub-block image is separated recursively into different sub-images with the cumulative density function (CDF). Then,each sub-image histogram is equalized within its respective gray range,and all the sub-images are incorporated into the equalized sub-blocks. Both linear and bilinear interpolations are used in the equalized sub-block based on a step size to avoide the generation of blocking effects and the influence on image details. Experimental results show that the average Peak Signal Noise Ratio(PSNR) is improved by 0.063~6.633 dB compared with those of traditional interpolation methods. In fact,the local image details are enhanced,and the input image brightness is also preserved effectively. For the influence of the blocking effects on the image is eliminated,the equalized image shows a more natural visual impression.