A communication method and a related apparatus. The communication method includes determining, based on a starting location of a first remaining minimum system information RMSI detection window and a time index of a synchronization signal (SS)/physical broadcast channel (PBCH) block, a starting location of an RMSI detection window corresponding to a terminal device, where a value of the starting location of the RMSI detection window is one of four possible values of the starting location of the RMSI detection window, and receiving the RMSI based on the starting location of the RMSI detection window.