Abstract: A detecting algorithm is proposed for the LSB replacement steganography in special domain. It is known that the LSB replacement steganography achieves embedding the secret message by changing the least significant bit of pixel's gray value, which maybe result in the asymmetry of the gray-level value. By means of this characteristic, the algorithm of steganalysis based on adjacent histogram is proposed. This algorithm is easily implemented and physical meaning is dislinct. The experiment results show that the proposed method has a better ability of detection.