Abstract: To enhance vertical mobility of CO₂ flooding, mitigate interlayer heterogeneity, and achieve accurate downhole flow measurement, a vortex flowmeter for measuring underground supercritical CO₂ flow was developed based on the selection of flowmeters, combined with the principle of Karman vortex street effect, structural design, and theoretical analysis. This flowmeter calculated the flow rate by detecting the frequency of vortex separation. Within the Reynolds number range of 4.73×10⁴ to 4.73×10⁵, the measurement results were not affected by the density or viscosity of the fluid. In the range of flow rates from 5 to 50 m³/d for the mixed fluids of white oil and water with different ratios, the correlation degree of the laboratory flow repetition test curves was approximately 100%, and the maximum relative error was only 1.73%. The field test showed that the differences between the actual injection volume and the allocated injection volume measured in the two wells at the site were in line with the engineering requirements. Research showed that the designed vortex shedding flowmeter can accurately measure the flow rate of underground supercritical CO₂, solving the problem of precise measurement of the flow rate of supercritical CO₂ in downhole small space. It provides a key tool for intelligent injection of carbon capture, utilization and storage (CCUS) and is of great significance for improving the efficiency of CO₂ flooding.