At present, the nozzle as gas flow transfer standard device is widely used in domestic and foreign testing organizations. In application, the selection of a single nozzle, a couple of nozzles or several nozzles depends on the required flow. Compared with the practical application of sonic nozzles abroad, domestic plants are different in such aspects as nozzle installation method, structure arrangement and the upstream design. In uncertainty evaluation, the interaction (numbers and positions) between nozzles should be considered. Two sets of sonic nozzle gas flow standard device from Beijing and Henan are chosen to measure two groups of similar flow points with turbine flow meter and calculate the deviation coefficients of different combinations of instruments. The uncertainty from this phenomenon is 0.02% and 0.07% respectively. Obviously, because of the nozzle processing, installation and use, two sets of sonic nozzle by means of experimental results are quite different. So the uncertainty analysis for the sonic nozzle device should consider this component. The job for evaluation of the standard device can be more scientific and accurate in this way.