This paper proposes a new symmetric information hiding scheme, aiming to increase the degree of disguise and the security. This scheme utilizes the randomness of the image cover itself to generate the secret key which has high randomness, so as to improve the effect of disguise of stego-objects and the security of information hiding scheme. In addition, this paper also proposes a new randomness test method，which can give more accurate quantitative test results and is suitable for testing the randomness of the cover. Experimental studies show that the new information hiding method can improve the degree of disguise of the stego-object and the security of the steganographic algorithm, and enhance the robustness of the information hiding to some extent.