This article considers the development of principles of modeling Organic Rankine Cycle (ORC) turbine stages for subsequent test rig studies with air as the working fluid. The article contains information about modeling a 280-kW ORC turbine stage with a hexametildisiloxane working fluid. The modeling process was carried out in the ANSYS software package. Four modeled regimes of the ORC turbine’s fractional load were calculated with minimum deviation of similarity criteria of the ORC and its air model turbine stages. A physical study of the air model of the ORC turbine was performed next at the test rig with air as a working fluid. The research showed that the integral characteristics of numerical calculation of the ORC turbine and its air model turbine have a deviation up to 3%. The obtained results allow to carry out experimental studies of air models of turbine stages on available test rigs when manufacturing ORC turbines in the future further if numerical calculation shows that organic working fluid simulation is possible. Further research can be aimed at studying the formation of vortex and stall zones at modeled regimes using five-channel probes and the PIV method (Particle Image Velocimetry).