A wireless transmission method, a base station, a relay station, and a mobile station using the same methods are proposed. The method is adapted for delivering MBS in a relay system, and includes following procedures. MBS data is transmitted by a base station at a first time point to at least a subordinate mobile station. The MBS data is also transmitted at the first time point or at a later time point from the base station to subordinate relay node(s) thereof. The base station and relay node(s) at an upper hop level decide whether to transmit a duplicate of the MBS data simultaneously with the relay node(s) at a lower hop level when the lower hop level relay node(s) is scheduled to transmit the received MBS data at the later time point. An indicator is used to indicate any two transmissions being identical.