This application discloses an image block prediction method. The method includes: obtaining a first reference line corresponding to a first prediction mode in at least two intra prediction modes corresponding to a target image block; determining, based on the first prediction mode and at least one second prediction mode, a second reference line corresponding to the second prediction mode, the second prediction mode being a prediction mode other than the first prediction mode in the at least two intra prediction modes; and fusing a first prediction block and at least one second prediction block, to determine a target prediction block corresponding to the target image block. The first prediction block is determined based on the first prediction mode and the first reference line, and each second prediction block is determined based on one second prediction mode and the second reference line.