The invention discloses a H.264/AVC video information hiding method based on a predictive mode. For a macro block whose coding mode is Intra 4*4 in an I chip, a predictive mode of a 4*4 luma block is modulated to a suboptimal predictive mode from an optimal predictive mode under the circumstance that the predictive mode of the 4*4 luma block needs to be changed, and for macro blocks whose coding modes are marked not by 0 in a P chip and a B chip, a coding mode of a macro block is modulated to a suboptimal predictive mode from an optimal predictive mode under the circumstance that the predictive mode of the macro block needs to be changed; the impact on the objective quality of a video, caused by the change of the predictive mode or the coding mode, can be reduced as much as possible under the circumstance of ensuring that the secret information can be effectively hidden at the same time; on the other hand, due to the fact that the secret information not only can be embedded in the macro block whose coding mode is Intra 4*4 in the I chip but also can be embedded in the macro blocks whose coding modes are marked not by 0 in the P chip and the B chip, the higher hiding capacity can be obtained.