An inter-frame prediction method based on a merge with motion vector difference (MMVD) mode may include: constructing a first candidate list of a current coding block in the MMVD mode, wherein the first candidate list includes a first preset number of first candidate motion vectors (MVs); determining a second preset number of motion search amplitudes and a third preset number of motion search directions; taking the first candidate MV as a starting point, and searching by different motion combinations of the motion search amplitudes and the motion search directions, to obtain a MV offset of the first candidate MV under the different motion combinations, for each of the first candidate MVs; determining to obtain an optimal MV of the current coding block based on the MV offset of each of the first candidate MVs in the different motion combinations.