The present disclosure relates to a 5G or 6G communication system for supporting a higher data transmission rate. The present disclosure relates to a method and apparatus for improving security of a user plane in a communication system by enhancing security of a protection key to be used in the user plane. A method by which a base station operates in a wireless network system, according to an embodiment of the present disclosure, may comprise the steps of: generating, by a CU-CP or CU-UP included in the base station, a user plane protection key for integrity protection of at least one piece of data or signaling transmitted or received on a user plane, on the basis of protection key generation information of the base station; transmitting, to a terminal, protection key generation information of the terminal for generating the user plane protection key; and applying the user plane protection key to the at least one piece of data or signaling transmitted or received on the user plane with the terminal.