T he biggest utilization of geothermal energy is currently processing geothermal energy into electricity. A geothermal project so that it can be developed and produce electricity if the field is feasible and can be profitable from the economic side. One of the development of geothermal projects in Indonesia is the Lahendong Area which is owned by PT. Pertamina Geothermal Energy with a generating capacity of 1X20 MW. Then an economic study is carried out for geothermal development projects with a capacity of 1X20 MW so that the feasibility level from the economics of the geothermal development project to several economic indicators is used, including the Net Present Value (NPV), Internal Rate of Return (IRR), and Pay Out Time (POT). The calculation in this study uses basic data input obtained from PT. Pertamina Geothermal Energy and the Indonesian Geothermal Association, the results of the calculation show that the field is not feasible to develop. From the simulation of the calculations carried out, some of the most influential parameters to achieve a decent economy, the field must be adjusted for the selling price (tariff), drilling cost, and EPCC (Engineering, Procurement, Construction, Commissioning) of the project. In the sector the benchmark price for purchasing energy prices based on the cost of producing new and renewable energy (feed in tariff) is set by the benchmark selling price of each province in the 2018 Generation Cost of Supply (BPP) by the Indonesian Ministry of Energy and Mineral Resources at a rate of US $ 13.46 cents / kWh. However, after the economic calculation is done, the results show that the tariffs for projects in the region are not economical and that there needs to be a readjustment and the tariff must be in the range of at least US $ 15 cents / kWh to be economical. However, if the fixed rate adjusts to the benchmark price based on BPP Generation 2018, by reducing the drilling cost and EPCC costs, the project can be feasible to be developed from the economic side