The efficient recovery and utilisation of sinter waste heat resource is quite important to reduce the energy consumption of sintering process. Due to the characteristics of low temperature sinter cooling flue gas without the dew point corrosion, the outlet flue gas of sinter waste heat boiler is introduced into the organic Rankine cycle (ORC) system. Based on the methods of theoretical analysis and numerical calculation, the variations of performance index of ORC system with the flue gas temperature at the outlet of evaporator under different evaporation temperature of working medium and pinch-point temperature difference in the evaporator are investigated by selecting the R245fa as the working medium of ORC system. The results show that, both the net put power and exergy efficiency of ORC system gradually decrease with the increase of flue gas temperature at the outlet of evaporator for a given evaporation temperature of working medium. When the pinch-point temperature difference in the evaporator is constant, both the net output power and exergy efficiency of ORC system tend to increase first and then decrease with the increase of flue gas temperature at the outlet of evaporator. In addition, with the increase of pinch-point temperature difference in the evaporator, the flue gas temperatures at the outlet of evaporator corresponding to the maximum net output power and exergy efficiency of ORC system all increase linearly. When the pinch-point temperature difference in the evaporator increases by 5°C, the flue gas temperature at the outlet of evaporator corresponding to the maximum net output power increases by 5°C, while the flue gas temperature at the outlet of evaporator corresponding to the maximum exergy efficiency increases by 10°C.