Embodiments of the present invention disclose a relay method of a transport bearer, an apparatus and a communication system. According to the technical solutions in the present invention, when receiving information encapsulated by a source device and sent by the source device, a relay base station first decapsulates the information, encapsulates the information again, and then sends the encapsulated information to a host device, thus ensuring that the information has only a layer of encapsulation in the transport procedure, so as to avoid a case that a high overhead caused by two layers of encapsulation occurs in the transport procedure. Compared with the prior art, the overhead in the transport procedure may be reduced, and the transport efficiency may be increased.