An apparatus and method for improving Radiated Spurious Emission (RSE) performance of a multi-standby terminal supporting 3rd Generation (3G) and/or 4th Generation (4G) service is provided. The method for enhancing RSE performance of a multi-standby terminal including an antenna for transmitting and receiving 2nd Generation (2G) and 3G band signals, a Radio Frequency (RF) switch for switching between the 2G and 3G band signals, a 2G communication unit connected to the RF switch for transmitting and receiving 2G band signals, a 3G communication unit connected to the RF switch for transmitting and receiving 3G band signals, and a transceiver for processing the 2G and 3G band radio signals includes determining a frequency band by checking a user identity card, switching, when the recognized frequency band is the 3G band, the RF switch to establish a connection between the antenna and the 3G communication unit, and disabling the 2G communication unit.