A method and a device for data relay transmission in a wireless relay communication network are provided, in which, the relay station directly obtains corresponding egress CID related information based on input MAC PDUs, then generates output MAC PDUs including the egress CID related information, and at last, according to the egress CID related information, performs QoS scheduling for the output MAC PDUs, so as to output them in an sequence of QoS. The invention omits the steps of de-cascading, de-segmenting or de-capsulating the MAC PDUs in order to obtain MAC SDUs, and the steps of scheduling by category, cascading, segmenting, and encapsulating the MAC SDUs in order to re-generate the MAC PDUs in the prior art, and the invention simplifies the data processing procedure and achieves the goal of decreasing the relay latency.