The present disclosure relates to relay communication methods and apparatuses. In one example method, a relay device receives first information sent by a host device, and performs relay forwarding based on the first information. The first information is used to determine whether the relay device turns on an amplify-and-forward function on a first time domain resource unit in a first time domain resource set, the first time domain resource set includes one or more time domain resource units, and the first time domain resource unit is any time domain resource unit in the first time domain resource set.