In this study, to develop and verify the Jeju-type groundwater thermal system design program, the energy consumption and system performance derived by input into the design program based on the load calculated on the demonstration site and the groundwater temperature were compared and analyzed with the actual measured values. The theoretical values ​​of energy consumption and heating and cooling COP ​​obtained through the Jeju-type groundwater thermal system design program were 11.24kW, 5.28 for heating, 13.31kW, 3.94 for cooling respectively. The measured values ​​of energy consumption and COP of the Jeju-type groundwater thermal system were 3967.2kW and 4.5, respectively. The error between the theoretical value and the measured value obtained through the design program is 0% and 2.39%, respectively. The errors that occur in the predicted values ​​and the actual values ​​are due to variables that are ignored in the system assumptions. If users consider errors and use it when designing groundwater thermal systems, they can estimate the cost of required drilling works, heat exchangers, and heat pumps and analyze economic feasibility.