Geothermal energy is one of the most promising renewable energies due to its independence of climate. As clean energy demands increasing all over the world, how to use this kind of energy economically and environmentally becomes increasingly important. So far, geothermal energy can be utilized to meet buildings’ heat and cool demand and electricity generation. Usually, there are two kinds of systems implemented to extract geothermal energy according to the circulating way of heat-carrier fluid, open loop system and closed loop system. However, the temperature variation in geothermal reservoir is still uneasy to predict while exploiting geothermal energy because of the complicated coupling processes. In this context, OpenGeoSys, as an open source numerical software, has proven to be an powerful tool to simulate and evaluate the Thermal-Hydraulic-Mechanical-Chemical (THMC) processes, will be used to investigate the performance and sustainability of geothermal system. In my research, simulating the system of Deep Borehole Heat Exchanger (DBHE) coupled Ground Source Heat Pump (GSHP) wound be the first two year's task, which is mainly utilized to extract deep geothermal energy for building heating. After that, a typical open loop system called Enhanced Geothermal System will be studied for better design of the geothermal plant.