An encoding and decoding method, where the decoding method includes obtaining first information of a coding tree unit (CTU) in a to-be-decoded picture from a bitstream, where the first information indicates an allowed value range of a width-to-height ratio of a coding unit (CU) obtained by dividing the CTU, obtaining division information of the CTU from the bitstream, dividing the CTU into one or more CUs based on the first information and the division information, where a width-to-height ratio of the one or more CUs falls within the value range indicated by the first information, and the plurality of CUs do not overlap each other, and decoding the one or more CUs to obtain a reconstructed pixel of the one or more CUs.