The disclosure relates to a communication technique of converging a 5th generation (5G) communication system for supporting higher data rates after a 4th generation (4G) system with Internet of things (IoT), and a system therefor. The disclosure provides a method performed by a first network entity managing a packet data network (PDN) session in a wireless communication system supporting interworking between a first and second networks. The method comprises receiving subscription update information of a user equipment (UE) for which a PDN connection associated with a network slice is established in the second network, the network slice being subscribed in the first network, determining whether to release the PDN connection if the subscription update information includes information notifying that network slice related information of the UE is changed, and performing a release of the PDN connection associated with the network slice if the release of the PDN connection is determined.