Abstract: The 3’cDNA fragment of KsNHX1 in Kochia sieversiana was obtained by RACE. The phylogenetic analysis of antiporters from different plant species indicated that the KsNHX1 was a gene encoding vacuolar Na⁺/H⁺ antiporter. By using semi-quantitative RT-PCR, the expression profiles of the KsNHX1 under different saline-alkali stresses were examined. It was observed that the transcript of KsNHX1 in leaves under the stress of 200 mmol·L^-1 for 2-24 h increased gradually with increasing duration, and the expression of KsNHX1 in roots, stems, leaves, and flowers under the stress of 200 mmol·L^-1 for 10h was up-regulated. Under various NaCl concentrations, the expression of KsNHX1 in leaves was up-regulated, with the maximum under 160 mmol·L^-1 of NaCl. The expression of KsNHX1 in roots was also up-regulated under the stress of <400 mmol·L^-1. Under various concentrations of Na₂CO₃, the expression of KsNHX1 in roots appeared the similar change patterns with those under corresponding concentrations of NaCl, but the expression of KsNHX1 in leaves was down-regulated except under 160 mmol·L^-1. The changes of the expression patterns implied that KsNHX1 played roles in maintaining the homeostasis of K⁺/Na⁺, which probably contributed to the saline-alkali tolerance of Kochia sieversiana.