Abstract: A steady analysis code on the direct helium turbine cycle system of high-temperature gas-cooled reactor was developed. The model includes reactor core, steam generator, gas turbine, compressor and heat exchanger modular. The startup procedure of gas turbine system was simulated and analyzed. The surge of compressor was also studied and the effects of heat transfer capacity, temperature and pressure were analyzed. The result shows that the compressor has enough safety margins in the load change procedure of gas turbine system.