Abstract: The measurement value of a ventilation rate standard bar is influenced by ambient conditions, therefore a device for the routine check of the standard bar was designed. Electronic soap film flowmeters are used to measure the total airflow and ventilation airflow separately. A differential pressure gauge is adopted to measure the pressure difference between the inlet end and outlet end of the standard bar. A baremeter is used to measure the ambient air pressure. The ventilation rate is obtained by calculation. Three ventilation rate standard bars with certified value of 27.87%, 58.83% and 71.95% separately were tested, the results showed that their values measured by the designed device were 27.03%, 58.32% and 71.37% respectively, and the errors between the measured values and the certified values were all less than 1% with the expanded uncertainty of 1.42% (k=2), which met the requirements of routine check. This technology provides a support for promoting the accuracy and reliability of the ventilation rate measurement with standard bar.