A video picture prediction method and apparatus are provided, to provide a manner of determining a maximum length of a candidate motion vector list corresponding to a subblock merge mode. The method comprises: parsing a first indicator from a bitstream; if the first indicator indicates that a candidate mode used to inter predict the to-be-processed block comprises an affine mode, parsing a second indicator from the bitstream, where the second indicator is used to indicate a maximum length of a first candidate motion vector list, and the first candidate motion vector list is constructed for the to-be-processed block, a subblock merge prediction mode is used for the to-be-processed block; and determining the maximum length of the first candidate motion vector list based on the second indicator.