Provided are a method for performing port configuration of a 5G system (5GS) for providing a time synchronization service, and a network entity performing the same. A method for performing port configuration may include: when a grandmaster (GM) is determined to be a Time Sensitive Networking (TSN) GM outside the 5GS, performing, by a Network Exposure Function (NEF), port configuration of the 5GS in a Best Master Clock Algorithm (BMCA) scheme; and when the GM is determined to be a 5GS GM inside the 5GS, or the TSN GM outside the 5GS that does not support the BMCA, performing, by the NEF, port configuration of the 5GS in an external port configuration scheme.