The experiments, about entrainment performance, as well as mass transfer efficiency, of multidowncomer (MD) sieve tray were investigated in a 1200-min-diameter tower with air/water system. The results indicate that the entrainment rate of MD sieve tray is lower and its behavior with increased liquid rate contradicts that of the conventional sieve tray. According to the nonmonotone variation phenomenon of entrainment at various liquid loads given by Lu and Kister, we developed the Double-Transition Point Theory to interpret the entrainment features under different contact regimes and the entrainment mechanism of MD sieve tray. By comparing the correspondence match of entrainment, pressure drop, and efficiency curves, we discussed the operating upper limit and mass-transfer efficiency. Therefore, based on the formulas of Yell's and Hunt's correlations, we developed the model for MD sieve tray where a semitheoretical derivation on entrained droplets in the froth regime was made.