|To increase the energy conversion efficiency of geothermal resource, the paper proposes two-stage geothermal power system, the thermodynamic performance between double flash and flash-binary power system is compared basing on numerical simulation, the applicable conditions of different power system are also discussed in the paper. The simulation result shows that, when the geothermal resource temperature between 80-130 °C, the net power output of two stage flash geothermal power system is higher than flash-binary system by maximum value 19.4%; when the geothermal resource temperature between 130-150 °C, the net power output of flash-binary geothermal power system is higher than two stage flash system by maximum value 5.5%. However, the sum water gas production of double flash power system is 2-3 times than flash-binary power system, which will cause the bigger volume of equipment and higher cost of power system. When the temperature lesson than 130 °C, it is better to use flash-binary power system because the flash pressure of double system is in vacuum which will consume more power for running vacuum pump. When the temperature is higher than 130 °C, it is better to use double flash power system because of low initial and operation cost.