The 5-nitroguaiacol sodium (5-NGS,10 μmol·L^-1) was applied to spray 10cm height of Chinese chives (cv.Dajingou).The nitrate content,key enzyme activities of nitrogen metabolism,amino acid components,nutritional quality and chlorophyll a fluorescence were measured and compared with control treatment (spraying water) at 12 d.The results showed that:(1)5-NGS significantly enhanced activities of nitrate reductase(NR),glufaminc synthctasc(GS),glutamate oxaloacetate transaminase(GOT),glutamate pyruvate transaminase(GPT) by 58.7%,26.5%,179.4%,131.3%,and the nitrate content reduction by 26.1%.(2)5-NGS significantly enhanced soluble protein,Vc contents by 49.5%,25.0%,respectively.Significantly higher contents of 15 kinds of amino acids were also observed in 5-NGS-treated leaf than that in control leaf of Chinese chives.However,soluble sugar content in 5-NGS-treated leaf was lower than that in control leaf.(3)5-NGS significantly enhanced biomass,leaf area,chlorophyll content,and increased electron transport rate(ETR) by 11.3%.Thus,the ability of 5-NGS to increase nitrate reductase(e.g.NR) and higher nitrogen assimilation enzyme(e.g.GS,GOT,GPT) activities might be an important attribution linked to low nitrate accumulation in leaves of Chinese chive.