Disclosed herein are a real-time gas turbine simulation system and an execution method thereof, capable of verifying input and output signals of an actual gas turbine control system (GTCS) by simulating a gas turbine in real time to reduce trial and error in power plant operation in a gas turbine power generation system. The real-time gas turbine simulation system simulates a gas turbine to verify a GTCS for controlling a gas fuel through an actuator/sensor module and a safety integrity level (SIL) protection function through a protection module for the gas turbine, and includes a hardwire-in-the-loop (HIL) simulator connected to the actuator/sensor module and the protection module through one or more hardwires to simulate a time critical portion of the gas turbine in real time, and a network simulator connected to the GTCS through a network to simulate a non-time critical portion of the gas turbine in real time.