A communication method and a communication apparatus are provided. The method includes: An optical line terminal (OLT) may obtain a cycle period and a data amount of periodic data, and allocate a first slot and a second slot based on the data amount of the periodic data and the cycle period, where the first slot is used to transmit the periodic data, the second slot is used for windowing, and the second slot is a part or all of slots other than the first slot in the cycle period. The OLT uniformly allocates the first slot used to transmit the periodic data and the second slot used for windowing.