Organic Rankine Cycle is an effective technology for low-grade waste heat power generation. In this paper, the thermal-dynamic performance of ORC system, in which low-temperature waste heat (from 40-140℃) is used as heat source, was evaluated with software RefProp8.0. The result indicates that in the range of low temperature, the working fluids like R601, R601a, R600a, R141b, R245fa and R245ca have better thermal performance. Furthermore, pilot-scale experiment using R245fa as working fluid was conducted, which validated the operation of the system for low-grade waste heat recovery. Finally, the economic feasibility of ORC has been analyzed for an ORC system using the waste heat from quenching water of blast furnace slag (80℃). According to the analysis, the project is reasonable in economy because the recovery period of investment is less than 4.2 years and environment-friendly since the CO2 can be reduced by almost 43650.68t annually.