Abstract: For the under-construction 10 MW compressed air energy storage (CAES) demonstration system, the internal flow characteristics and energy consumption distribution features of the adjustable ejector were analyzed based on computational fluid dynamics simulation. An effective exhaust gas suction method was determined according to the actual operating conditions, and the effects of nozzle spacing, air storage tank operating pressure and needle process on the ejection performance of the adjustable ejector were investigated. Results show that under high back pressure conditions, the ejector can recover pressure energy by sucking exhaust gas through the central nozzle. The nozzle spacing may restrict the ejection performance by affecting the energy consumption of the internal flow field of the ejector. When the nozzle spacing is 22.5 mm, the maximum mass flow rate of the exhaust gas ejected into the turbine for work is 2.65 kg/s. Meanwhile, the ejection ratio of the adjustable ejector first increases and then decreases as the operating pressure reduces, and increases as the needle process decreases. When the operating pressure is 9.0 MPa, the maximum ejection ratio is 11.4%.