Abstract: This paper presents a new model of stego-channel based on the digital images.It takes account of the steganalysis and similarity between cover-image and stego-image, considering the probability of error and probability of detection as distortion constraints.It applies game theory to steganography.It regards the encoder-decoder and attacker as the two players in the game, analysing the steganographic capacity under different distortion constraints.At last, it discusses the results of the steganographic capacity base on the game theory.