400RT geothermal system which is consist with vertical-typed 112 geothermal heat exchangers is measured and evaluated in spring, 21st${sim}$24th May 2008. As the results, the average temperature difference between inlet and outlet of geothermal pipes is $1{sim}2^{circ}C$ and that of cool water supply is $2{sim}6^{circ}C$, when being normally operated. Despite temperature fluctuations by cooling loads, the average temperature difference between main pipes of inlet and outlet of geothermal heat exchangers is measured as $3^{circ}C$. The geothermal system COPs are calcluated as 2.92${sim}$3.92 in every 12 hours.