A decoding method, an encoding method, an encoder, and a decoder are provided. The decoding method includes that: determining, by parsing a bitstream, last significant coefficient location reverse identification information of a current slice, and coordinate information of a last significant coefficient of a current block of blocks in the current slice; in response to the last significant coefficient location reverse identification information indicating that last significant coefficient location reverse is applied to the blocks in the current slice, obtaining a location of the last significant coefficient of the current block by performing calculation on the coordinate information of the last significant coefficient; and determining coefficients of the current block by decoding coefficients located above the location of the last significant coefficient in a preset scanning order.