Abstract:The characteristics of transpiration in leaves of Liriodendron chinense seedlings measured by a CI-30lPS Portable Photosynthesis System showed that the highest transpiration rate in soil withsufficient water appeared in the afternoon of sunny summer. The leaf/air temperature difference,stomatal conductance, reactive humidity and other factors markedly affected the transpiration rate.The daily average water use effidency of L. chinense sablings was 4.142 mmol CO2 mol-1 H2O.