The present invention discloses a transmission method and system for a Relay Physical Downlink Control Channel (R-PDCCH). The method comprises the steps of: an eNB bearing downlink grant information of a relay node onto an available Orthogonal Frequency Division Multiplex (OFDM) symbol of a first slot of a pre-allocated Physical Resource Block (PRB) pair used for bearing the R-PDCCH, wherein available OFDM symbols in the PRB pair, other than the OFDM symbol used for the downlink grant information, are used for bearing a Physical Downlink Shared Channel (PDSCH) of each relay node; the eNB transmitting the PRB pair bearing the downlink grant information and the PDSCH to the relay node. The present invention is well applicable to a link between an eNB and a relay node, and meanwhile enables backhaul resources to be used adequately.