A method includes: selecting, from M polar codes of a same code length and code rate, a polar code corresponding to an actual code rate for a first transmission, and encoding an information bit sequence by using the polar code to obtain encoded bits; and performing rate matching on the encoded bits to generate to-be-sent bits. Different from a traditional HARQ using one polar code, in this embodiment, a polar code corresponding to the actual code rate for the first transmission is selected from the M polar codes during the initial transmission, so that a different polar code can be selected adaptively according to the actual code rate for the first transmission.