Disclosed are a method and an encoder for performing polar coding on an input data sequence to generate a polar code. The encoding method including: generating, based on a first order index set, a second order index set for parent code length of the polar code, each order index of the first or second order index set representing a priority order of transmitting an information bit in a bit position indicated by the order index relative to transmitting information bits at bit positions indicated by other indexes; spreading, according to the second order index set, the input data sequence to a data sequence with bit number equal to the parent code length; performing polar coding on the spread data sequence to generate the polar code.