Method and device for image prediction

The invention provides a method and a device for image prediction. The method comprises the steps of: obtaining a first reference unit of an image unit, wherein the image unit and the first reference unit obtain respective predicted images by using the same affine model; obtaining motion information of basic motion compensation units at the at least two preset positions of the first reference unit; and obtaining the motion information of the basic motion compensation units of the image unit. Therefore, by multiplexing the motion information of the first reference unit which adopts the same affine pre-model, a motion vector of the current image unit is obtained more exactly, the coding and decoding complexity is kept while the prediction accuracy is improved, and the coding and decoding performance is improved.