Vortex flowmeter is a flowmeter based on the principle of fluid oscillation to measure the flow rate, but the output signal at low flow rate is very weak, in the actual measurement process will superimpose a variety of on-site noise. At present, the small diameter vortex flowmeter used in industry has measurement limitations under small flow conditions, and the minimum diameter is generally only DN15. Aiming at the existing problems of vortex flowmeter, the structure and parameters of small diameter vortex flowmeter DN10 and below are studied, to meet the new measurement requirements in industry. Based on the simulation calculation platform, the numerical calculation model of the micro-diameter vortex flowmeter with different size parameters is established and the simulation calculation is carried out, and the optimized structure size of the vortex flowmeter is proposed. By studying the intensity and frequency of pressure fluctuation at different pressure monitoring points, the best position of sensor is analyzed. Finally, the electromagnetic flowmeter is used as the standard table to test the developed micro diameter vortex flowmeter in the micro range. The error and accuracy of the flowmeter are tested, and the relationship between Re and St and the instrument coefficient are analyzed. The results show that the measurement characteristics obtained by simulation are in good agreement with those measured by experiment. The relative error of the micro diameter vortex flowmeter is better than 0.5%, repeatability and other indicators can meet the measurement standards in the micro-range.