A two temperature CO2 refrigeration system with economizer is proposed and compared with the traditional dual-temperature CO2 refrigeration system based on energy consumption, exergy and economic analysis. Using genetic algorithm multi-objective optimization method, taking the COP, exergy loss and total economic cost as the objective functions to find the best design conditions of the two systems. The Pareto fronts are obtained at different ambient temperatures. Technique for order preference by similarity to an ideal solution decision-making method is adopted to determine the optimum state points. The simulation results show that when operating at different ambient temperatures, the introduction of economizer can improve COP, reduce exergy loss and the overall economic cost rate of the two-temperature CO2 refrigeration system. In addition, economic analyses take the impact of carbon dioxide emission cost and electricity price into consideration. The results indicate that with the increase of CO2 emission cost and electricity price, the hourly economic cost of both systems increases, but the hourly economic cost of the two-temperature CO2 refrigeration system with economizer system is always lower than that of conventional two-temperature CO2 refrigeration system.