A hydroponic culture experiment was conducted to study on the physiological characteristics and growth of Apium graveolens L.var.dulce DC.seedlings under the different NO₃^- concentration (0，1，5，10，15，50，100 and 150 mmol·L^-1).The results showed that：(1)With NO₃^- concentration increased（1～50 mmol·L^-1），the heights,biomass,shoot/root ratio and leaf area of the seedlings increased;the absorption of N,P,and K nutrients improved;the content of chlorophyll and the MDA increased;and the activities of POD and CAT increased.(2)When the NO₃^- concentration was equal to or higher than 100 mmol·L^-1,the biomass and the content of chlorophyll decreased;the absorption of P,and K nutrients reduced;the MDA,soluble protein and sugar content，SOD activity appeared its highest peak;and the activities of POD and CAT decreased.We can concluded that the NO₃^- concentration of 15 mmol·L^-1 favored the growth of celery;and the NO₃^- concentration of 100 mmol·L^-1 caused the nitrate stress to the plant growth and resulted in injury to membrane lipid peroxidation，but the antioxidation enzyme and osmatic adjustment substance could adjust themselves to avoid nitrate stress harms,which led to some tolerant ability of Apium graveolens L.var.dulce DC to nitrate stress condition.