In order to investigate the relief effect of exogenous nitric oxide donor sodium nitroprusside on plants under copper stress,Jatropha curcas was chosen.The effects of different concentrations of SNP and CuCl₂ on the growth of J.curcas seedlings were investigated and the appropriate concentrations of SNP (0.2 mmol/L) and ²⁺ (90 mmol/L) were selected.Then the effects of SNP on the contents of proline,malondialdehyde and antioxidant enzyme activities under ²⁺ stress were studied.The results showed that:(1)²⁺ treatments increased the contents of proline and MDA,the activities of catalase (CAT),superoxide dismutase (SOD),guaiacol peroxidase (POD) and ascorbic acid specificity peroxidase (APX).(2)The pretreatment with SNP could further enhance the content of proline(Pro),the activities of CAT,SOD,POD and APX,decrease the MDA content under ²⁺ stress in seedling leaves.In general,0.2 mmol/L SNP can markedly relieve the oxidative stress by increasing the antioxidative enzymes’ activities and the free proline content,enhancing antioxidative ability of J.curcas seedlings under ²⁺ stress.