The characteristics of salinity ions distribution in soiltree system change under salt stress because many physiological activities of trees are changed,which influences the absorption of water and selectiveabsorption of ions by roots.In this project,the rhizoboxes experiments were randomized completely designed,with application of NaCl to furnish 0,1,and 2 g/kg NaCl,to study the transportation and distribution of K+,Na+,Ca2+,and Mg2+ in soilpoplar systems under NaCl stress in greenhouse.The main results indicated that the watersoluble K+ in rhizosphere were lower than that in nonrhizosphere,but Na+,Ca2+,and Mg2+ were accumulated in rhizosphere under three NaCl treatments.The two poplar clones,I69(Populus deltoides Bartr.cv.’Lux’) and NL1381(the highbred of I69 and P.euramericana(Dode) Geninier CL ’E45/51’),could absorb K+,Ca2+,and Mg2+ more selectively than Na+ under 1 g/kg NaCl treatment,and improve the selective transportation of Ca2+(clone I69) or K+,Ca2+,and Mg2+(clone NL1381)to the aerial parts.