The present invention discloses a video decoding method and a video decoder. The method includes: parsing coding tree split information to obtain a current node; determining, based on a depth N of the current node, a region covered by a current quantization group; obtaining a quantization parameter QP delta of a current coding unit CU in the region covered by the current quantization group; and obtaining a reconstructed picture of the current CU based on the QP delta of the current CU. By using the present invention, decoding efficiency can be improved.