Abstract: Although the Optimal Parity Assignment（OPA） steganography has the characteristics of good concealment and small distortion，it will be revealed for it’s generated binary image，which color is confused.This paper proposes an improved OPA steganography method，which introduces the color intensity into the color sets of the OPA to optimize the color parity assignment.The new method can eliminate the effect of the confused color in the generated binary image，and keep the high stego-data quotiety at the same time.SHA-1 algorithm is also introduced to implement the new stego-data algorithm，which improves the security of the new method.