Performance analysis of Trans-critical N2O ejector expansion refrigeration cycle is analyzed. Two phase ejector, an expansion device is used instead of conventional expansion device. Performance analysis is carried out on basis of three thermodynamic parameters mainly 'COP, Refrigerating effect (R.E.) and compressor work 'and two main performance parameters called 'Entrainment Ratio and Pressure Recovery Ratio'. The resulting parameters of N2O cycles are compared with that of CO2 cycle performance parameters. The N20 ejector expansion system is found to have higher COP, lower compressor discharge pressure and higher Entrainment ratio but lower volumetric cooling capacity.