A polar code segment encoding method and a related apparatus are disclosed, and the method includes: determining, based on an information bit quantity of a first information bit sequence and a first code rate, a target code length for polar code encoding; determining an initial code length based on the target code length, where the initial code length is an integer multiple of a smallest segment code length; dividing the first information bit sequence into S segments of information bit sequences based on the first code rate and the initial code length and when the initial code length is different from the target code length, performing rate matching on the S segments in a process of performing polar code encoding on the S segments of information bit sequences, where a sum of segment code lengths of the S segments is the target code length after the rate matching.