A method for intra prediction of a picture block, comprising: constructing a first luma intra mode set for a current block, wherein the first luma intra mode set is a subset of a plurality of preset candidate luma prediction modes, and is a set of most probable intra prediction modes; and the first luma intra mode set comprises a determined luma prediction mode of a picture block that is not spatially adjacent to the current block in a picture in which the current block is located; parsing a received bitstream to obtain a first identifier; when the first identifier indicates that a luma prediction mode of the current block belongs to the first luma intra mode set, parsing the bitstream to obtain a second identifier, wherein the second identifier is used to indicate which candidate luma prediction mode in the first luma intra mode set is used as the luma prediction mode of the current block; and obtaining a luma prediction value of the current block based on the luma prediction mode of the current block; characterized in that the current block has a width of w pixel set basic units and a height of h pixel set basic units, the picture in which the current block is located comprises M groups of picture blocks not spatially adjacent to the current block, and each group of picture blocks not spatially adjacent to the current block has a group number, wherein a picture block with a group number i comprises picture blocks in which pixel set basic units in the following coordinate positions in a virtual coordinate system are located: (-i×w,-i×h), (1+m×w,-i× h), (-m×w,-i×h), (-i×w,-m×h), and (-i×w,m×h+1), wherein m is an integer in a range from 0 to i - 1; M, i, w, and h are positive integers; i is not greater than M, and a value of i is not 1; and in the virtual coordinate system, a position, in the picture, of a pixel set basic unit at the bottom-right corner of the current block is used as an origin, a straight line on which the bottom boundary of the current block is located is used as a horizontal coordinate axis with a rightward direction as a positive horizontal direction, and a straight line on which the right boundary of the current block is located is used as a vertical coordinate axis with a downward direction as a positive vertical direction. constructing a first luma intra mode set for a current block, wherein the first luma intra mode set is a subset of a plurality of preset candidate luma prediction modes, and is a set of most probable intra prediction modes; and the first luma intra mode set comprises a determined luma prediction mode of a picture block that is not spatially adjacent to the current block in a picture in which the current block is located; parsing a received bitstream to obtain a first identifier; when the first identifier indicates that a luma prediction mode of the current block belongs to the first luma intra mode set, parsing the bitstream to obtain a second identifier, wherein the second identifier is used to indicate which candidate luma prediction mode in the first luma intra mode set is used as the luma prediction mode of the current block; and obtaining a luma prediction value of the current block based on the luma prediction mode of the current block; characterized in that the current block has a width of w pixel set basic units and a height of h pixel set basic units, the picture in which the current block is located comprises M groups of picture blocks not spatially adjacent to the current block, and each group of picture blocks not spatially adjacent to the current block has a group number, wherein a picture block with a group number i comprises picture blocks in which pixel set basic units in the following coordinate positions in a virtual coordinate system are located: (-i×w,-i×h), (1+m×w,-i× h), (-m×w,-i×h), (-i×w,-m×h), and (-i×w,m×h+1), wherein m is an integer in a range from 0 to i - 1; M, i, w, and h are positive integers; i is not greater than M, and a value of i is not 1; and in the virtual coordinate system, a position, in the picture, of a pixel set basic unit at the bottom-right corner of the current block is used as an origin, a straight line on which the bottom boundary of the current block is located is used as a horizontal coordinate axis with a rightward direction as a positive horizontal direction, and a straight line on which the right boundary of the current block is located is used as a vertical coordinate axis with a downward direction as a positive vertical direction.