The present disclosure relates to a method and apparatus for key relay control based on software-defined networking in a quantum key distribution network. A method of controlling key relay in a quantum key distribution network (QKDN) according to an embodiment of the present disclosure includes: receiving, by a first control entity, a key relay route request from a key management (KM) layer; determining, by the first control entity, whether or not key relay is associated with a plurality of resource groups; and, transmitting a key relay route request from the first control entity to a second control entity, when key relay is associated with the plurality of resource groups, wherein key relay route information produced by the second control entity may be provided to the KM layer.