Abstract: In order to effectively utilize the saturated liquid working fluid after flash evaporation of organic flash cycle（OFC）and improve the recovery efficiency of medium and low temperature heat sources,a double-stage organic flash cycle system with ejector（DEOFC）driven by geothermal water is established,the influence of key parameters on the system is explored,and the system is optimized with multiple objectives. The results show that when the flash pressure and the outlet pressure of the high-pressure expander of DEOFC are optimal,with the increase of heat source temperature,the net output work,thermal efficiency and exergy efficiency of the system show the trend of increase,which change when the temperature rises to the characteristic temperature of the working medium.When performing multi-objective optimization,R601a shows the best performance. Compared with the single-stage organic flash cycle with ejector（SEOFC）system,DEOFC has great advantages in net output work and exergy efficiency.