Thetreespecieselectionisthecriticalpartintheprocessofvegetationrestorationandreconstructioninaridandsemi-aridareas.Asareliableindicatorofdroughtresistanceandwaterusecharacteristicsoftreespecies,wateruseefficiency（WUE）hasbecomeahotspotintheresearchontreespecieselection.ThispaperintroducedtheconceptandcorrespondinglyresearchmethodofleafWUEandsummarizedtheresearchprogressofleafWUEintermsofthevariationinleafWUEbetweenspecies,positionsinthecanopy,andcharacteristicsoftemporalandspatialvariation,itsinfluenceonenvironmentalfactorslikeillumination,moisture,temperature,CO2andO3concentrations.Furthermore,itputforwardtheproblemscurrentlyexistingintheresearchandprospectedthetrendoffutureresearchonleafWUE.
