By using Gilibrator-2 electronic soap film flowmeter, the system flow of scanning mobility particle sizer (SMPS) was calibrated. Aerosol generator was also used to test the accuracy of measuring particle size. The result indicates that before the system flow of SMPS was calibrated, there is a deviation between the values of sample flow and sheath flow on SMPS panel and the correspondingly actual values of them. The diameter in peak is 274.3 nm before the flow on panel is calibrated. Measuring diameter in peak of aerosol particles is 198.7 nm after calibration. The deviation between standard size and measuring result reduces from 36.1% to 2.1%. Size distribution and number concentration of aerosols were also compared and analyzed before and after the SMPS flow was calibrated.