Embodiments of this application provide a polar code encoding and decoding method and apparatus. The method includes: obtaining an information bit set from a polar code construction sequence table based on an information bit length and a target code length of to-be-encoded information, where the polar code construction sequence table stores a mapping relationship between an encoding parameter and a construction sequence corresponding to the encoding parameter, the construction sequence is a sequence representing an order of reliability of polarized channels, and the encoding parameter includes at least one of an aggregation level, the target code length, and a mother code length, or the encoding parameter is a maximum mother code length; and performing polarization encoding on the to-be-encoded information based on the to-be-encoded information and the information bit set.