Abstract: A method and apparatus for controlling power in a decode-and-forward (DF) relay system is provided. The method of controlling power in a DF relay system includes: acquiring first channel information of a first link between a source node and a destination node, second channel information of a second link between the source node and a relay node, and third channel information of a third link between the relay node and the destination node, by using a pilot signal; determining a power level of the source node from the acquired first through third channel information; and feeding back the determined power level to the source node and the relay node.