Abstract: The features of push-pull ventilation were introduced. In order to investigate the flow characteristics of low velocity push-pull ventilation, a series of experiments were carried out with different space between air diffuser and air suction (interval L=3.5~3.8m). The results showed that low velocity push-pull airflow enters conflux before jet origination finishing while L<3.8m(There was no jet main section in flow field). The axial velocity of high velocity push-pull ventilation varied following power function. There was large deviation between the empirical equation of high velocity push-pull ventilation and experiments of low velocity push-pull ventilation. The former is not fit for low velocity push-pull ventilation. Therefore, the empirical equations of high velocity push-pull ventilation are not suitable for representing the peculiarities of low velocity push-pull ventilation.