Abstract: In measurement and control system of Gas Flow Standard Apparatus(GFSA),the pressure,volume change and temperature of gas in variable chamber are measured by capacitance diaphragm gauges,grating meters and platinum resistance thermometer.The fluctuation of pressure in variable chamber is controlled within±0.01% by a computer when gas flow is measured. Automatic control and management of GFSA are realized by software.The gas flow in the range of(17.1～1.22)×10-5PaL/s can be measured by GFSA, uncertainty is about 1.93%. Now,reference leaks and gas flowmeters have been calibrated by GFSA.