The invention discloses an H.264 compressed domain-based image depth map generation method, which comprises the following steps of: inputting an H.264 compressed domain code stream of an original image; decoding a length-variable entropy, extracting relevant characteristics of coding blocks in the code stream, and computing the prediction residual energy of the coding blocks; computing the tagged values of the coding blocks according to the prediction residual energy, normalizing, and dividing regions of the image; respectively computing average depth values of the regions and taking the average depth values as the depth values of all coding blocks of the regions to obtain the depth values of all coding blocks of the whole image so as to obtain the depth map of the coding blocks of the whole image; and performing Gaussian filtering and up-sampling on the obtained depth map of the coding blocks so as to obtain the depth map with the size same as that of the original image. In the method, the image depth map is extracted by using the internal information of the H.264 compressed code stream, and the image depth is analyzed at the level of the coding blocks, so that the method has high computation efficiency, and the obtained depth map is approximate to the real object depth.