Abstract: By applying exotic ABA and zeatine,it was found that P. euphr-atica could reduce salt influx in two ways after sensing salt stress:①closing stomatal could reduce transpiration and therefore reduce ion influx by mass flow;②enforcing ion selectivity could reduce ion influx of harmful elements and increase ion influx of nutritional elements,which would alleviate salt stress Furthermore,Ca²⁺ contents in xylum sap under ABA treatment were 6times as much as that under control,indicating that P. euphratica could transport more Ca²⁺ to leaf under stress condition The high concentration of Ca²⁺ can maintain membrane integrity in one hand,and induce closure of stomatal in the other hand Thus it can be concluded that Ca²⁺ is a salt resistance signal for P. euphratica.