The ORC (organic Rankine cycle) system has the advantages of simple structure, environmental friendliness,reliability and low capital cost. The expander is the key device of energy conversion in the ORC system, and itsperformance has a direct influence on that of the ORC. In this paper, a self-designed and manufactured radialinflow turbine is applied to low temperature waste heat power generation. The numerical model for the internalflow of the radial inflow turbine is established, and the numerical results show a better agreement with theexperimental data. Firstly, the influence of blade stagger angles on nozzle performance is studied. The studyfinds that with the decrement of stagger angles under specific angle ranges, the velocity coefficient increases.However, the efficiency of the nozzle decreases sharply when the stagger angle exceeds 30°. Secondly, theinfluence of the blade profile on the efficiency of the rotor is investigated. The results indicate that with tincreasing, the efficiency of the rotor firstly increases, then decreases quickly. It increases by 1% compared withthat of the original rotor, when the t=1.95. At last, the performance of the turbine is researched numerically.This paper discovers that total-to-static efficiency of the turbine increases by 1.7% compared with that of theoriginal turbine. This research provides orientation and basis for the improvement of aerodynamic design andperformance of radial inflow turbine. As for practical application, the study can provide certain reference for thestructure and blade profile design of nozzles and rotors to further improve the performance, and to offer somedata for the operational control and tests.