To match for the different temperature of the geothermal resource and strengthen the flexibility of organic Rankine cycle (ORC), this paper proposes a variable capacity power generation superstructure based on Flash and ORC for geothermal energy. A combined Flash-ORC experimental prototype is established to investigate its performance on both steady and dynamic conditions in this paper. Pressured hot water is adopted as the extensive worldwide existed hydrothermal geothermal resource, eliminating the influence of the used heat transfer oil on evaporating process. The experiment results show that there is an optimal mass flow rate of R245fa under the condition of different heat source temperature; Flash and binary power system dominate the flash-binary power system respectively when the heat source temperature are 120 ℃and 130℃;The isotropic efficiency of modified compressor just between 0.2 and 0.25; the power output of per geofluid mass flow rate are 0.78 kWh·t-1and 1.31 kWh·t-1 respectively when the heat source temperature are 120 ℃and 130℃.