A new data hiding method-multi-pixel value differencing(MPVD) steganography based on wet paper codes is presented.Firstly the cover image is divided into many unlapped blocks by using the way of raster scanning,each of which includes four pixels.Secondly the differences between each pixel and the minimal pixel in the block are gotten;the principle of wet paper writing is used in the differences,the dry place of which is selected to embed the scrambled secret message by the improved Arnold method,which is suitable to the human visual resolution capacity.With this algorithm,both the high capacity of embedding and security are ensured and the extraction is easy.The experiment results prove the validity of the proposed algorithm.