A method for coding a video, comprising: determining (S110; S210; S310) an estimated quantization parameter of a target picture in a target group of pictures, wherein the target GOP is associated to a video to be coded; determining (S120; S220; S320) an inter-picture change degree of the target GOP; determining (S130; S330) a propagation ratio of a target picture block in the target picture to a reference picture block in the target picture based on the estimated quantization parameter of the target picture and the inter-picture change degree; and coding (S140; S250) the video to be coded based on the propagation ratio; characterized in that, determining (S120; S220; S320) the inter-picture change degree of the target GOP comprises: determining the inter-picture change degree based on the number of target pictures in the target GOP and an intra-picture block ratio of the target GOP, in which the intra-picture block ratio is a ratio of the number of picture blocks of intra-picture prediction in the target GOP to the number of picture blocks of inter-picture prediction in the target GOP; wherein the coding (S140; S250) the video to be coded based on the propagation ratio comprises: determining a quantization parameter of the target picture block based on the propagation ratio and a propagation algorithm; and coding the video to be coded based on the quantization parameter of the target picture block. determining (S110; S210; S310) an estimated quantization parameter of a target picture in a target group of pictures, wherein the target GOP is associated to a video to be coded; determining (S120; S220; S320) an inter-picture change degree of the target GOP; determining (S130; S330) a propagation ratio of a target picture block in the target picture to a reference picture block in the target picture based on the estimated quantization parameter of the target picture and the inter-picture change degree; and coding (S140; S250) the video to be coded based on the propagation ratio; characterized in that, determining (S120; S220; S320) the inter-picture change degree of the target GOP comprises: determining the inter-picture change degree based on the number of target pictures in the target GOP and an intra-picture block ratio of the target GOP, in which the intra-picture block ratio is a ratio of the number of picture blocks of intra-picture prediction in the target GOP to the number of picture blocks of inter-picture prediction in the target GOP; wherein the coding (S140; S250) the video to be coded based on the propagation ratio comprises: determining a quantization parameter of the target picture block based on the propagation ratio and a propagation algorithm; and coding the video to be coded based on the quantization parameter of the target picture block. determining the inter-picture change degree based on the number of target pictures in the target GOP and an intra-picture block ratio of the target GOP, in which the intra-picture block ratio is a ratio of the number of picture blocks of intra-picture prediction in the target GOP to the number of picture blocks of inter-picture prediction in the target GOP; wherein the coding (S140; S250) the video to be coded based on the propagation ratio comprises: determining a quantization parameter of the target picture block based on the propagation ratio and a propagation algorithm; and coding the video to be coded based on the quantization parameter of the target picture block. determining a quantization parameter of the target picture block based on the propagation ratio and a propagation algorithm; and coding the video to be coded based on the quantization parameter of the target picture block.