A filtering method for intra-frame and inter-frame prediction. For a pixel value obtained by prediction, whether to filter a prediction block is self-adaptively chosen by means of an RDO decision; and a filter is established based on a generalized Gaussian distribution function, and different filters are used for prediction blocks of different sizes, and filter parameters are obtained by training the prediction blocks of each size. The method comprises performing RDO on each coding unit on a coding end, and firstly performing intra-frame prediction or inter-frame prediction on each coding unit; then filtering the prediction blocks using the filtering method of the present invention, and determining whether to use prediction block filtering by means of an RDO decision; at a decoding end, configuring different filtering coefficients for different prediction block sizes; and decoding according to a mark. Therefore, the problem of prediction block distortion is solved, and the prediction precision can be improved, improving the coding efficiency of an intra-frame and inter-frame prediction block.