The objectives of this experiment were to study the effects of foliarspraying nitric oxide (NO) on N metabolism enzyme activities and nutrients of Reaumuria soongorica seedlings leaves and roots under NaCl stress and to determine the ability of exogenous NO to alleviate NaCl stress in R. soongorica seedlings. The currentyear R. soongorica seedlings were used as test material to measure the activities of glutamine synthetase (GS), glutamate synthetase (GOGAT) and nitrate reductase (NR), the concentrations of soluble protein, free amino acid and NO^-₃ N in roots and leaves by different concentrations of NO (0, 0.01, 0.10, 0.25, 0.50 and 1.00 mmol·L^-1 sodium nitroprusside) under 300 mmol·L^-1 NaCl stress in this pot experiment. Principal component and subordinate function analysis were used to select the best N metabolism indexes and optimal NO concentration for evaluating the ability of NO to alleviate NaCl stress in R. soongorica seedlings. The results showed that: (1) GS, GOGAT and NR activities and soluble protein and NO^-₃ N concentrations all decreased significantly under 300 mmol·L^-1 NaCl stress. (2) Exogenous NO can significantly increase GS, GOGAT and NR activities and nitrate nitrogen concentrations in R. soongorica roots and leaves, and increase soluble protein and free amino acid concentrations in roots. (3) NR and GOGAT activities can be used to evaluate the mitigation effect of NO on R. soongorica seedlings under NaCl stress and order of the mitigating effect of exogenous NO on R. soongorica seedlings under NaCl stress is 0.25 mmol·L^-1SNP > 0.50 mmol·L^-1 SNP > 0.10 mmol·L^-1SNP > 1.00 mmol·L^-1SNP > 0.01 mmol·L^-1SNP by principal component and subordinate function analysis. The study found that 300 mmol·L^-1 NaCl stress inhibited N metabolism. Exogenous NO helped R. soongorica seedlings adapt to NaCl stress by increasing NR activities and promoting NO^-₃N transformate to NH⁺₄ and by promoting the assimilation of NH⁺₄ via the GS/GOGAT cycle in R. soongorica roots and leaves. The results showed that 0.25 mmol·L^-1SNP treatment was the most effective for alleviating NaCl stress in R. soongorica seedlings. NR and GOGAT activities can be used to evaluate the ability of NO to alleviate NaCl stress in R. soongorica.