LSB substitution steganography only takes the least significant bits in the cartier into account, which has the problems about low security and poor robustness.This paper proposes a self-contained steganography combining the MSB matching and LSB substitution.This paper proposes two types of encoding rules to define the matching result between the secret information binary stream and the most two-significant-bit stream of cartier, then keep/replaces the least two bits in every byte according to the corresponding matching result.Experiments show that the PSNR by this method is close to 60dB.Compared with traditional LSB substitution method, it has good robustness and concealment and improves the security and capacity, and to some extent, it increases the volume of a carrier.