A relay communication system and a method for transmitting data in the same system, wherein the method for transmitting data comprises: a relay station notifying a transmitting terminal and a receiving terminal of air interface resources which are required when the transmitting terminal transmits data and when the receiving terminal receives the data (S102); the transmitting terminal transmitting the data to the relay station on the air interface recourses, and the relay station forwarding the data to the receiving terminal on the air interface resources (S104). By using the present invention, the times of forwarding the data along a data transmission path can be effectively reduced, and thus improves data transmission efficiency.