Low content of available magnesium （Mg） in soils is prevalent across the main lemon-producing regions in China， leading to the frequent symptoms of Mg deficiency in lemon trees and compromising the yield and quality of fruits.A hydroponic sand culture experiment was conducted on lemon saplings grafted onto rootstocks of P. trifoliata and C35 citrange to study the differences in the uptake of nutrients in young lemon trees with different rootstocks under Mg-deficient stress and screen out rootstocks of lemons resistant to magnesium deficiency.Four treatments including P. trifoliata-grafted lemon-normal magnesium （Z1）， P. trifoliata-grafted lemon-magnesium deficiency （Z0）， C35 citrange-grafted lemon-normal magnesium （C1）， and C35 citrange-grafted lemon-magnesium deficiency （C0）， were set up， with two levels of magnesium including normal magnesium （1 mmol/L MgSO₄·7H₂O） and magnesium deficiency （0 mmol/L MgSO₄·7H₂O）.The content and transportation coefficient of nutrients in different tissues and organs were measured after 180 days of cultivation.Results showed that the uptake and utilization efficiency of Mg in P.trifoliata-grafted saplings was high under the normal Mg treatment.The content of Mg in the old and new leaves of P. trifoliata-grafted saplings was 26.08% and 15.91% higher than that of C35 citrange-grafted saplings respectively， with stronger capacity for enriching Mn and Cu.Mg deficiency resulted in transportation coefficient of N in both rootstock rootstocks being below 0.5.C35 citrange-grafted saplings had higher utilization efficiency of Mg and poorer ability to transport Ca， Fe， Mn， and Zn under Mg deficiency.Mg deficiency significantly increased the absorption of Mn in P. trifoliata-grafted saplings， with a risk of Mn toxicity.The results of comprehensive analyses showed that C35 citrange rootstock offers distinct advantages for Yunning No.1 under the cultivation condition of Mg deficiency but sufficient supply of other nutrients， whereas traditional P. trifoliata rootstock is more suitable in environments where multiple nutrients are generally scarce.