The invention discloses a final-section model stage with a flow coefficient of 0.007 of a single-axis CO2 compressor and a design method of an impeller. The final-section model stage with the flow coefficient of 0.007 of the single-axis CO2 compressor and the design method of the impeller mainly aim at improving efficiency of a CO2 compressor unit, reducing power consumption of the CO2 compressorunit, guaranteeing a wide working condition range for the compressor, and meanwhile being capable of improving stability of a rotor. The model stage comprises the impeller, a blade diffuser, a curve and a backflow device, wherein the impeller is a low-friction wedge-shaped impeller designed according to a specific blade thickness reference rule, and the impeller is located at the inlet position ofthe model stage; the outlet of the impeller is provided with the blade diffuser, the backflow device is located at the outlet position of the model stage, and the blade diffuser communicates with thebackflow device through the curve; and the machine mach number Mu2 of the model stage is equal to 0.6-0.9, the flow coefficient Phi1 is equal to 0.007, the energy head coefficient of a design point Tau is equal to 0.62, variable efficiency Eta pol of each mach number is equal to 0.66-0.665, and the flow range applied ranges from 73% to 139% of the design point.