A communication method and apparatus. The method comprises: on the basis of the length of a first sequence and L, a first apparatus determining the number B of time-domain units for resource subsets, and sending a first channel on the resource subsets, wherein the first sequence is used for extending the first channel, L is the number of times a first part of a first redundancy version is repeatedly transmitted in the resource subsets, and B is a positive integer. The method can prevent total resources scheduled within the number of repetitions from being insufficient due to extension, such that in the total resources scheduled within the time of repetitions, an extended first channel is correctly mapped into the total resources, thereby ensuring the correct transmission of the first channel to the greatest extent.