Abstract: To explore the alleviating effect of exogenous NO on radish under aluminum stress, the radish variety Chunhong 1 treated with high concentration(0.5 mmol·L^-1) aluminum stress and sodium nitroprusside（SNP） were used as experimental material and NO donor material respectively to study the effects of different concentrations of SNP(0 μmol·L^-1,25 μmol·L^-1,50 μmol·L^-1,100 μmol·L^-1,150 μmol·L^-1 and 200 μmol·L^-1) on radish seed germination and seedling physiological characteristics under aluminum stress.The results showed that high concentration of aluminum ion inhibited the growth of radish.Applying 100 μmol·L^-1 SNP could promote the germination of radish seeds and increase the photosynthetic pigment content of radish seedlings.Simultaneously, the activities of peroxidase（POD）,superoxide dismutase（SOD）,catalase（CAT） and ascorbate peroxidase（APX） were increased, and the O₂^·- production rate and H₂O₂ content in root tip were decreased.The results indicated that the suitable concentration of NO could effectively relieve the toxicity of aluminum stress to radish seeds and seedlings.