A method of decoding implemented by a decoding device, comprising: obtaining a video bitstream; decoding the video bitstream to obtain a value of chroma format indication information for a current coding block; obtaining an initial intra prediction mode value for chroma component of the current coding block; obtaining a mapped intra prediction mode value for chroma component of the current coding block according to a predefined mapping relationship and the initial intra prediction mode value, when the value of chroma format indication information for the current coding block is equal to a predefined value, wherein the predefined value is 2, the predefined value being 2 represents that the chroma format is 4:2:2; obtaining a prediction sample value for chroma component of the current coding block according to the mapped intra prediction mode value; characterized in that the following table is used to show the predefined mapping relationship, mode X 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 mode Y 0 1 61 62 63 64 65 66 2 3 5 6 8 10 12 13 14 16 mode X 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 mode Y 18 20 22 23 24 26 28 30 31 33 34 35 36 37 38 39 40 41 mode X 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 mode Y 41 42 43 43 44 44 45 45 46 47 48 48 49 49 50 51 51 52 mode X 54 55 56 57 58 59 60 61 62 63 64 65 66 mode Y 52 53 54 55 55 56 56 57 57 58 59 59 60 wherein mode X represents the initial intra prediction mode value, mode Y represents the mapped intra prediction mode value; wherein 0 represents planar mode, 1 represents DC mode, 2 to 66 represent angular modes, each of 2 to 66 corresponds to a predefined prediction direction. obtaining a video bitstream; decoding the video bitstream to obtain a value of chroma format indication information for a current coding block; obtaining an initial intra prediction mode value for chroma component of the current coding block; obtaining a mapped intra prediction mode value for chroma component of the current coding block according to a predefined mapping relationship and the initial intra prediction mode value, when the value of chroma format indication information for the current coding block is equal to a predefined value, wherein the predefined value is 2, the predefined value being 2 represents that the chroma format is 4:2:2; obtaining a prediction sample value for chroma component of the current coding block according to the mapped intra prediction mode value; characterized in that the following table is used to show the predefined mapping relationship, mode X 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 mode Y 0 1 61 62 63 64 65 66 2 3 5 6 8 10 12 13 14 16 mode X 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 mode Y 18 20 22 23 24 26 28 30 31 33 34 35 36 37 38 39 40 41 mode X 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 mode Y 41 42 43 43 44 44 45 45 46 47 48 48 49 49 50 51 51 52 mode X 54 55 56 57 58 59 60 61 62 63 64 65 66 mode Y 52 53 54 55 55 56 56 57 57 58 59 59 60 wherein mode X represents the initial intra prediction mode value, mode Y represents the mapped intra prediction mode value; wherein 0 represents planar mode, 1 represents DC mode, 2 to 66 represent angular modes, each of 2 to 66 corresponds to a predefined prediction direction. <EOS>