A rotor blade (10) of a wind power plant having a first and a second duct (16, 17) running inside the rotor blade (10) for conducting an air flow (21, 22) is provided. A method for de-icing a rotor blade (10) of a wind power plant is also provided. The rotor blade has a partition device (15) which separates the ducts (16, 17) from one another, such that the first duct (16) is arranged on a first side of the partition device (15) at the pressure side (26) of the rotor blade (10), and the second duct (17) is arranged on a second side of the partition device (15) at the suction side (25) of the rotor blade (10). In the method, the flow speed of the air flow provided in the first and second duct (16, 17) is predefined at least in portions of the rotor blade (10).