The disclosure relates to a method and a device for controlling a data rate in a network slice of a wireless communication system. A method for controlling a bit rate of a network slice by a session management function (SMF) device of a wireless communication system is provided. The method includes receiving a slice control policy information from a policy and charging function (PCF) device, transmitting, to a user plane function (UPF) device, a parameter for controlling each slice based on the received slice control information, and receiving, from the UPF device, a response signal for whether the transmitted parameter is acceptable.