Abstract: Reversible data hiding technique embeds data into host image using the reversible transform. The embedded data can be extracted correctly at the receiver side and the original image can be restored from the stego-image completely. These good performances make reversible data hiding technique have better applications in image information hiding technique. This paper analyzes the change of the single pixel and the change of the relationship between the pixel pair after using the Difference Expansion (DE) algorithm, and proves that the slidewindow can increase the capacity effectively. To prevent the reduction of the image quality, an improved log function is used to reduce the difference between the pixel pair in DE algorithm. Experiment results show that the use of slide-window can increase the embedding capacity from 0.5 bpp to 1bpp .and the comparison with Lou’s algorithm also show that the proposed algorithm can not only increase embedding capacity, but also can improve the stego-image’s quality