The present invention discloses a Time Division Dual (TDD) system and a downlink feedback method for a relay link thereof. A relay station and a network side of the TDD system transmit uplink data and downlink feedback through relay subframes, wherein: one or more uplink subframes are selected from uplink subframes of a wireless frame as uplink relay subframes used for uplink data transmission, a downlink subframe is determined for each uplink relay subframe from downlink subframes of the wireless frame as a downlink relay subframe used for downlink feedback or new data indication, wherein the uplink relay subframes and the downlink relay subframes have a fixed timing sequence relationship; the relay station transmits uplink data to the network side through the uplink relay subframes, and receives the downlink feedback or new data indication from the network side through the downlink relay subframes corresponding to the uplink relay subframes.