Abstract: The heat flowrate and pressure dorp of CO 2 in a multi-tube-in-tube helical coil type gas cooler were predicted using LMTD method and compared with the experimental data. The mass flowrate of CO 2 and coolant were varied from 0.06 to 0.075 [kg/s], and the cooling pressure of gas cooler were from 8 to 1 0 [MPa], respectively. The LMTD method is used to predict the heat flowrate and pressu re drop of supercritical CO 2 during in-tube cooling. The equations used by LMTD method were Gnielinski correlation for CO 2 and Dittus-Boelter correlation for coolant, respectively. The equation used to predict the pressure drop of CO 2 and coolant is Blasius correlation. In comparison of heat flowrate and pressure drop o f CO 2 measured by experiment to that predicted by LMTD method, the experimental heat flowrate and pressure drop of CO 2 in the multi-tube-in-tube helical coil type gas cooler shows a relatively good agreement with that predicted by LMTD method. Key words: Helical coil type gas cooler, CO