Abstract: According to the characteristics that the outlet water temperature of low temperature solar collectors is between 65 ℃ and90 ℃,this paper uses the principle of organic Rankine cycle power generation and simulates its performance by the software EES. The performance of organic Rankine cycle power generation system using six working fluids including R134a,R152a,R600a,RC318,R600,R245fa are thus analyzed and compared. The results show that in the studied temperature range,the evaporation pressure,evaporation temperature,system net power generation,electrothermal efficiency and system heat absorption are in direct proportion to the change with heat source temperature. When the heat source temperature is 90 ℃,the net power output and system efficiency of RC318 system are the highest,which are 12.27 kW and 15.42%. When the heat source temperature is 85 ℃,the exergy efficiency of RC318 system reaches the highest value which is 82.52%.