A video encoding method and apparatus is provided. The method includes determining a chroma format of a video frame, determining, for a currently decoded first quantization matrix (QM), a size of the first QM according to the determined chroma format and a size of a luma transform block (TB) when the first QM is a chroma QM, and decoding the first QM when the size of the first QM is greater than zero. Thus, a size of a chroma QM is flexibly determined according to a chroma format and a size of a luma TB, rather than a fixed size predefined according to an identifier of the QM, thereby improving flexibility during encoding and decoding of the chroma QM. Apparatus and non-transitory computer-readable storage medium counterpart embodiments are also provided.