A method of video decoding performed in a video decoder, comprising: receiving a bit stream including syntax elements, the syntax elements corresponding to residues of a transform block in a coded picture; determining a first maximum number of context-coded bins of the syntax elements of a first coefficient sub-block in the transform block based on a frequency position of the first coefficient sub-block in the transform block, wherein the frequency position is a coordinate pair, in the units of coefficient sub-block width and height, of the first coefficient sub-block relative to a top-left coefficient sub- block in the transform block; coding each of a number of bins of the syntax elements of the first coefficient sub-block according to a context model and the determined first maximum number of the context-coded bins of the syntax elements of the first coefficient sub-block; and decoding coded bits of the number of the bins of the syntax elements of the first coefficient sub-block based on the context models, wherein the first maximum number of context-coded bins of the syntax elements of the first coefficient sub-block is different from a second maximum number of context-coded bins of the syntax elements of a second coefficient sub-block in the transform block, and characterized in that the frequency position of the first coefficient sub-block is in a low frequency region of the transform block, and the first maximum number of the context-coded bins of the syntax elements of the first coefficient sub-block is larger than an average maximum number of context-coded bins of syntax elements of coefficient sub-blocks in the transform block. receiving a bit stream including syntax elements, the syntax elements corresponding to residues of a transform block in a coded picture; determining a first maximum number of context-coded bins of the syntax elements of a first coefficient sub-block in the transform block based on a frequency position of the first coefficient sub-block in the transform block, wherein the frequency position is a coordinate pair, in the units of coefficient sub-block width and height, of the first coefficient sub-block relative to a top-left coefficient sub- block in the transform block; coding each of a number of bins of the syntax elements of the first coefficient sub-block according to a context model and the determined first maximum number of the context-coded bins of the syntax elements of the first coefficient sub-block; and decoding coded bits of the number of the bins of the syntax elements of the first coefficient sub-block based on the context models, wherein the first maximum number of context-coded bins of the syntax elements of the first coefficient sub-block is different from a second maximum number of context-coded bins of the syntax elements of a second coefficient sub-block in the transform block, and characterized in that the frequency position of the first coefficient sub-block is in a low frequency region of the transform block, and the first maximum number of the context-coded bins of the syntax elements of the first coefficient sub-block is larger than an average maximum number of context-coded bins of syntax elements of coefficient sub-blocks in the transform block.