The present disclosure relates to a method and apparatus for motion vector derivation for affine based inter prediction of chroma subblocks based on a chroma format. The method includes: determining chroma scaling factors in horizontal and vertical directions based on chroma format information, wherein the chroma format information indicates a chroma format of a current picture which the current image block belongs to; determining a set of luma subblocks of the luma block based on values of the chroma scaling factors; and determining a motion vector for a chroma subblock of the co-located chroma block based on motion vectors of one or more luma subblocks in the set of luma subblocks.