The present disclosure relates 5G or pre-5G communication systems for supporting higher data transmission rate than those by LTE or other post-4G communication systems. Disclosed are a method and apparatus for determining a window size in a wireless communication system. The method includes determining an uplink data rate of the UE on a wireless link, determining that a maximum data size transmittable through an internet session including the wireless link is the window size for the internet session based on the uplink data rate, and transmitting uplink data through the internet session based on the determined window size.