An intra prediction method for a video sequence, wherein a separation tree structure is used for an intra picture in the video sequence, comprising: obtaining (S601; S701) a size and a split mode of a chroma coding tree node; determining (S602; S701), based on the size and the split mode of the chroma coding tree node, whether to allow cross-component linear model, CCLM, intra prediction to be performed on a chroma coding unit included in the chroma coding tree node; determining (S603; S701) a prediction mode of the chroma coding unit depending on whether to allow CCLM intra prediction to be performed on the chroma coding unit; and processing (S604; S701) the chroma coding unit based on the prediction mode of the chroma coding unit to obtain prediction samples of the chroma coding unit, wherein the size of a luma coding tree node corresponding to the chroma coding tree node is T1 × T1, wherein T1 is a preset threshold that is equal to 64, the luma coding tree node is split using a quadtree split mode, and the size of the chroma coding tree node is M × N, wherein the determining, based on the size and the split mode of the chroma coding tree node, whether to allow CCLM intra prediction to be performed on a chroma coding unit included in the chroma coding tree node further includes: when both M and N are equal to T1, if the split mode of the chroma coding tree node is either no splitting or a quadtree split mode, determining to allow CCLM intra prediction to be performed on the chroma coding unit, or if the split mode of the chroma coding tree node is neither no splitting nor a quadtree split mode, determining not to allow CCLM intra prediction to be performed on the chroma coding unit; or when M is equal to T1 and N is equal to T1/2, if the split mode of the chroma coding tree node is either no splitting or a vertical binary split mode, determining to allow CCLM intra prediction to be performed on the chroma coding unit, or if the split mode of the chroma coding tree node is neither no splitting nor a vertical binary split mode, determining not to allow CCLM intra prediction to be performed on the chroma coding unit. obtaining (S601; S701) a size and a split mode of a chroma coding tree node; determining (S602; S701), based on the size and the split mode of the chroma coding tree node, whether to allow cross-component linear model, CCLM, intra prediction to be performed on a chroma coding unit included in the chroma coding tree node; determining (S603; S701) a prediction mode of the chroma coding unit depending on whether to allow CCLM intra prediction to be performed on the chroma coding unit; and processing (S604; S701) the chroma coding unit based on the prediction mode of the chroma coding unit to obtain prediction samples of the chroma coding unit, wherein the size of a luma coding tree node corresponding to the chroma coding tree node is T1 × T1, wherein T1 is a preset threshold that is equal to 64, the luma coding tree node is split using a quadtree split mode, and the size of the chroma coding tree node is M × N, wherein the determining, based on the size and the split mode of the chroma coding tree node, whether to allow CCLM intra prediction to be performed on a chroma coding unit included in the chroma coding tree node further includes: when both M and N are equal to T1, if the split mode of the chroma coding tree node is either no splitting or a quadtree split mode, determining to allow CCLM intra prediction to be performed on the chroma coding unit, or if the split mode of the chroma coding tree node is neither no splitting nor a quadtree split mode, determining not to allow CCLM intra prediction to be performed on the chroma coding unit; or when M is equal to T1 and N is equal to T1/2, if the split mode of the chroma coding tree node is either no splitting or a vertical binary split mode, determining to allow CCLM intra prediction to be performed on the chroma coding unit, or if the split mode of the chroma coding tree node is neither no splitting nor a vertical binary split mode, determining not to allow CCLM intra prediction to be performed on the chroma coding unit. when both M and N are equal to T1, if the split mode of the chroma coding tree node is either no splitting or a quadtree split mode, determining to allow CCLM intra prediction to be performed on the chroma coding unit, or if the split mode of the chroma coding tree node is neither no splitting nor a quadtree split mode, determining not to allow CCLM intra prediction to be performed on the chroma coding unit; or when M is equal to T1 and N is equal to T1/2, if the split mode of the chroma coding tree node is either no splitting or a vertical binary split mode, determining to allow CCLM intra prediction to be performed on the chroma coding unit, or if the split mode of the chroma coding tree node is neither no splitting nor a vertical binary split mode, determining not to allow CCLM intra prediction to be performed on the chroma coding unit.