Embodiments of the present invention provide a video image encoding method and apparatus, and a video image decoding method and apparatus. The video image decoding method includes: parsing a high-resolution image bitstream, to generate a reconstructed image of a first-type sub-image and auxiliary information of the first-type sub-image, where the auxiliary information represents dimension information of the sub-image and position information of the sub-image in a decoder to-be-reconstructed image, the sub-image is a pixel set of any continuous area in the decoder to-be-reconstructed image, and sub-images of the decoder to-be-reconstructed image do not overlap with each other; when a complete decoder reconstructed image fails to be obtained based on the reconstructed image of the first-type sub-image, parsing a low-resolution image bitstream, to generate a reconstructed image of a second-type sub-image, where the second-type sub-image has a resolution the same as that of the first-type sub-image; and splicing the reconstructed image of the first-type sub-image and the reconstructed image of the second-type sub-image based on the auxiliary information, to generate the decoder reconstructed image.