Objective: A trans-critical CO₂ refrigeration system with ejector is proposed and its performance factors are studied. Methods: In this paper, energy and exergic system model combined with experiment method were used to study the impact of the change of major parameters on traditional and new refrigeration systems. Results: In a given working condition, exergy efficiency of the compressor increased by 11.08% when an injector replaced the throttle valve, while the power of the compressor decreased by 6.04% and the performance factor increased by 11.1%. The optimum gas cooler pressure was found to maximize the system performance. In addition, the exergic damage of the system components was optimized in this paper. Conclusion: The ejector of the new system has great potential for optimization, and the outlet temperature of the gas cooler has the greatest influence on the performance of the ejector.