An　adjustable　ejector　with　a　needle　is　deemed　as　an　effective　device　to　improve　the　performance　of　the　transcritical　CO2　refrigeration　cycle　with　a　wide　operating　conditions.　In　this　paper,　a　homogeneous　CFD　model　is　built　up　to　compare　the　performance　of　the　adjustable　and　fixed　ejectors　with　the　same　key　structural　sizes.　By　validating　the　numerical　results　with　the　experimental　data,　the　k-epsilon　RNG　and　k-epsilon　Realizable　are　considered　to　predict　the　performance　of　the　CO2　ejector　well.　Furthermore,　an　exergy　analysis　model　is　proposed　to　obtain　the　exergy　fluxes　of　the　primary　and　secondary　flows　are　obtained,　respectively.　The　results　discover　that　the　main　exergy　transfer　(interaction　between　the　primary　and　secondary　flows)　locates　in　the　suction　chamber.　Meanwhile,　the　higher　exergy　loss　is　observed　in　the　suction　chamber　of　the　adjustable　ejector　due　to　flow　separation　along　the　needle　and　higher　viscous　dissipation　of　oblique　shock　wave,　which　results　in　5%-11%　lower　entrainment　ratio　than　that　of　the　fixed　ejector.　However,　the　higher　velocity　in　the　fixed　ejector　results　in　higher　friction　of　the　wall　and　more　intense　flow　separation　in　the　diffuser　which　causes　higher　exergy　loss　in　the　mixer　and　diffuser.　Accordingly,　the　exergy　efficiency　of　the　adjustable　ejector　is　only　0.5%　lower　than　that　of　the　fixed　ejector.　In　spite　of　the　special　case　in　this　paper,　the　adjustable　ejector　is　considered　to　be　able　to　achieve　a　similar　exergy　efficiency　with　the　fixed　ejector.