The invention discloses a pneumatic turbine driven test bench. The pneumatic turbine driven test bench comprises a rotor system, a power system, a lubrication system, a test system and a safety system. An intermediate bearing is arranged between an inner rotor and an outer rotor; the outer rotor is driven by a pneumatic turbine; a control system is a feedback control system; compressed air drivesthe pneumatic turbine mounted on the outer rotor to rotate. After the compressed air provided by an air compressor enters a pressure stabilizing box, the compressed air flows through a pressure regulating valve and then flows out of a nozzle to impact the pneumatic turbine to drive the pneumatic turbine to rotate; the rotation speed of the outer rotor is detected by a rotation speed transmitter, and then the rotation speed is fed back to a rotation speed controller; the compressed gas flow is adjusted by controlling the opening of the pressure regulating valve to control the rotation speed ofthe outer rotor. In a supporting structure, squirrel cage elastic supports and elastic ring squeeze film dampers are combined, so that the stability of the rotors can be improved. The pneumatic turbine driven test bench can be used for the experimental study of the dynamic characteristics of the double rotor-support system with the coupling of the inner and outer rotors and the simulation and research of the rotor system vibration faults.