Indonesia is privileged with the world's largest geothermal energy reserves potential equal to 28.61 Gigawatt-electric (GWe). However, Indonesia's geothermal installed capacity currently is only around 2.13 GWe, far from their actual potential. Developing geothermal energy is necessary for Indonesia to enable Indonesia's sustainable energy systems. Enhancing geothermal energy development is becoming the goal of the government in the years to come. Herein, geothermal development is regarded as a complex dynamic system. As such, the complexity of geothermal development adds challenges to achieve the goal. This paper aims to understand and analyze the complex structure of geothermal development in Indonesia. For this purpose, the paper analyzes the geothermal development with a holistic and systematic approach using the conceptualization stage of the system dynamics approach. The conceptual model shows that many underlying factors affecting the development of geothermal energy in Indonesia. Further, the Feed-in Tariff seems to play the most significant role as the government intervention to enhance Indonesia's geothermal energy development.