To address persistent issues such as unclear application ranges and difficulties in structural optimization of composite tridimensional rotational flow sieve tray (CTRST)—primarily due to poorly understanding of gas-liquid cross-zone distribution mechanisms, experimental investigations were carried out to examine gas-liquid cross-zone distribution and flow loss mechanisms in both the packing and swirl zones of the CTRST. A key parameter, the net cross-zone flow proportion, was introduced for both gas and liquid phases to accurately quantify inter-zone flow conditions. The results revealed that, under the tested conditions, the net liquid cross-zone flow proportion varied between -0.325 and -0.370, with the net flow direction moving from the swirl zone to the packing zone. Conversely, the net gas flow ratio ranged from 0.022 to 0.310, showing a net flow from the packing zone to the swirl zone. By employing the net cross-zone flow loss ratio, the loss mechanisms during gas-liquid cross-zone transfer were further analyzed. It was observed that liquid spray density and gas kinetic energy factor had only a minor influence on the net inter-zone liquid phase loss flow rate percentage, suggesting that resistance to liquid phase exchange between zones was relatively low. In contrast, the gas phase loss flow rate ratio varied significantly from -0.047 to -0.319, indicating considerable resistance to gas phase interaction across zones. This ratio initially increased and then decreased with higher liquid spray density, reaching a peak at 92.26 m3/(m2?h). Additionally, it showed a gradual increase with higher gas kinetic energy factor. Based on these findings, a predictive model for the net cross-zone mass transfer rate was developed, which effectively correlated the influence of operational parameters with flow loss intensity. This model offers valuable theoretical support for further exploration of the gas-liquid cross-zone mass transfer distribution mechanism in CTRST systems, thereby aiding in the optimization of tray design and operational guidelines.