In this paper, we present a new steganographic method based on the pixel value differencing approach. The previous research of pixel value differencing can provide a better visual quality after embedding secret data than the well-known least-significant-bit (LSB) method but the embedding data capacity is much less than LSB method. We propose a new steganographic method by using pixel value differencing that hide secret data only in smooth areas, and this new method can provide much more hiding capacity than the previous research. The experimental results show the proposed method can hide much more data and keep a good visual quality of the stegoimage.