A hybrid automatic repeat request method of a downlink tunnel comprising the following steps: the base station transmits the tunnel data comprising the protocol data unit of multiple mobile stations to the access relay station via the tunnel link, and receives the feedback from the relay station until the access relay station receives the data correctly; the access relay station analyzes the protocol data unit of each mobile station from the tunnel data, transmits the protocol data unit of each mobile station to the corresponding mobile station, and performs the corresponding process after receiving the feedback from each mobile station.