In this paper, a solar organic Rankine cycle system with net output power of about 100 kW is designed. R600， R600a, R245ca ，R245fa ，R123, R113 and R227ea are selected as working fluids during the different evaporation temperature, and thermodynamic cycle characteristics of the ORC system was studied. The evaporation pressure, thermal efficiency, and irreversible loss were respectively calculated and compared. An organic radial turbine is designed and modeled for the system. The results show that R245fa, as the circulating working fluid of the solar organic rankine cycle system, creates relatively high thermal efficiency and produces relatively low total irreversible loss. According to the CFD calculation results, the internal flow state in the organic radial turbine is good and the streamline distribution is uniform, and the isentropic efficiency of turbine reaches 83.41%, which basically meets the design requirements.