A video picture prediction method, comprising: parsing, from a sequence parameter set, SPS, in a bitstream, a value of a first indicator sps_affine_enabled_flag and a value of a third indicator sps_sbtmvp_enabled_flag; wherein, the sps_affine_enabled_flag is used to specify whether an affine motion model may be used to inter predict on a picture block comprised in a video picture; and the sps_sbtmvp_enabled_flag is used to specify whether an advanced temporal motion vector prediction, ATMVP, mode can be used to inter predict a picture block comprised in a video picture; when the value of the first indicator is equal to 1, parsing a value of a second indicator five_minus_max_num_subblock_merge_cand from the SPS, determining a maximum length of a first candidate motion vector list MaxNumSubblockMergeCand, wherein a value of MaxNumSubblockMergeCand satisfies the following formula: MaxNumSubblockMergeCand = 5 − five _ minus _ max _ num _ subblock _ merge _ cand, wherein the first candidate motion vector list is a candidate motion vector list constructed for a to-be-processed block, a subblock merge prediction mode is used for the to-be-processed block; and when the value of the first indicator is equal to 0, determining the maximum length of the first candidate motion vector list MaxNumSubblockMergeCand, wherein, the value of MaxNumSubblockMergeCand satisfies the following formula: MaxNumSubblockMergeCand = sps _ sbtmvp _ enabled _ flag. parsing, from a sequence parameter set, SPS, in a bitstream, a value of a first indicator sps_affine_enabled_flag and a value of a third indicator sps_sbtmvp_enabled_flag; wherein, the sps_affine_enabled_flag is used to specify whether an affine motion model may be used to inter predict on a picture block comprised in a video picture; and the sps_sbtmvp_enabled_flag is used to specify whether an advanced temporal motion vector prediction, ATMVP, mode can be used to inter predict a picture block comprised in a video picture; when the value of the first indicator is equal to 1, parsing a value of a second indicator five_minus_max_num_subblock_merge_cand from the SPS, determining a maximum length of a first candidate motion vector list MaxNumSubblockMergeCand, wherein a value of MaxNumSubblockMergeCand satisfies the following formula: MaxNumSubblockMergeCand = 5 − five _ minus _ max _ num _ subblock _ merge _ cand, wherein the first candidate motion vector list is a candidate motion vector list constructed for a to-be-processed block, a subblock merge prediction mode is used for the to-be-processed block; and determining a maximum length of a first candidate motion vector list MaxNumSubblockMergeCand, wherein a value of MaxNumSubblockMergeCand satisfies the following formula: MaxNumSubblockMergeCand = 5 − five _ minus _ max _ num _ subblock _ merge _ cand, wherein the first candidate motion vector list is a candidate motion vector list constructed for a to-be-processed block, a subblock merge prediction mode is used for the to-be-processed block; and when the value of the first indicator is equal to 0, determining the maximum length of the first candidate motion vector list MaxNumSubblockMergeCand, wherein, the value of MaxNumSubblockMergeCand satisfies the following formula: MaxNumSubblockMergeCand = sps _ sbtmvp _ enabled _ flag.