A method for a colour component prediction, applied to decoder, characterized by comprising: acquiring a first reference sample set corresponding to a colour component to be predicted of a coding block in a video picture; when a number of available samples in the first reference sample set is equal to 0, taking a preset component value as a prediction value corresponding to the colour component to be predicted; and when a number of the available samples in the first reference sample set is greater than or equal to 4, screening the first reference sample set to obtain a second reference sample set; when a number of available samples in the second reference sample set is equal to a preset number, determining a model parameter through the second reference sample set, and obtaining a prediction model corresponding to the colour component to be predicted according to the model parameter, wherein the prediction model is used to implement a prediction processing of the colour component to be predicted to obtain a prediction value corresponding to the colour component to be predicted, wherein the screening the first reference sample set to obtain the second reference sample set comprises: determining positions of samples to be selected based on sample positions and/or colour component strength corresponding to neighbouring reference samples in the first reference sample set; and choosing, from the first reference sample set, available samples corresponding to the positions of the samples to be selected according to the determined positions of the samples to be selected, and determining the second reference sample set based on the chosen available samples, wherein the number of the available samples in the second reference sample set is less than or equal to the preset number. acquiring a first reference sample set corresponding to a colour component to be predicted of a coding block in a video picture; when a number of available samples in the first reference sample set is equal to 0, taking a preset component value as a prediction value corresponding to the colour component to be predicted; and when a number of the available samples in the first reference sample set is greater than or equal to 4, screening the first reference sample set to obtain a second reference sample set; when a number of available samples in the second reference sample set is equal to a preset number, determining a model parameter through the second reference sample set, and obtaining a prediction model corresponding to the colour component to be predicted according to the model parameter, wherein the prediction model is used to implement a prediction processing of the colour component to be predicted to obtain a prediction value corresponding to the colour component to be predicted, wherein the screening the first reference sample set to obtain the second reference sample set comprises: determining positions of samples to be selected based on sample positions and/or colour component strength corresponding to neighbouring reference samples in the first reference sample set; and choosing, from the first reference sample set, available samples corresponding to the positions of the samples to be selected according to the determined positions of the samples to be selected, and determining the second reference sample set based on the chosen available samples, wherein the number of the available samples in the second reference sample set is less than or equal to the preset number. determining positions of samples to be selected based on sample positions and/or colour component strength corresponding to neighbouring reference samples in the first reference sample set; and choosing, from the first reference sample set, available samples corresponding to the positions of the samples to be selected according to the determined positions of the samples to be selected, and determining the second reference sample set based on the chosen available samples, wherein the number of the available samples in the second reference sample set is less than or equal to the preset number.