This application provides a video picture decoding and encoding method and a video picture decoding and encoding apparatus. When it is determined that a merge or skip mode is used, if it is determined through decoding that a merge mode with motion vector difference (MMVD) indicator is true, a triangle prediction unit (PU) indicator may not be coded. The triangle PU indicator is coded when it is determined through decoding that the MMVD indicator is false. This reduces a quantity of used coding resources, and can reduce bit overheads of a bitstream.