Abstract: Characteristic parameters, qrR/λ_D are introduced as the temperature difference to non dimensionalize the governing equations,and then the similarity criteria for flow and heat transfer of rotor stator disks system are established.It is concluded that the study of cooling effects in the turbine disks should comprise not only Nusselts number for disk surface convective heat transfer,but also the non dimensional excessive averaged body temperature for total disk temperature level and the non dimensional radial temperature difference for the disk radial thermal stress.With resort to the concept of turbine blade cooling efficiency,an expression is derived for calculating the cooling efficiency of a turbine disk.