To investigate the effects of lanthanum on the antioxidant properties of wheat seedlings under chromium stress, wheat seedlings were treated with different concentrations of chromium chloride（CrCl₃） firstly to screen suitable concentrations of chromium in this study. Wheat seedlings were treated with different concentrations of LaCl₃（20, 60, 120 μmol/L） under chromium stress and the indictors related with the antioxidant properties were measured. The results showed that the contents of malondialdehyde（MDA）, hydrogen peroxide（H₂O₂） and ascorbic acid（AsA） in wheat seedlings were significantly increased by chromium stress. Meanwhile, the activities of superoxide dismutase（SOD） and glutathione reductase（GR） were significantly increased, the activities of ascorbate peroxidase（APX） and catalase（CAT） were significantly decreased. Exogenous LaCl₃ could significantly reduce the contents of MDA, H₂O₂ and AsA in wheat seedlings under chromium stress. Meanwhile, the activity of SOD was reduced and the activities of APX, GR and CAT were improved. It indicated that heavy metal chromium would cause peroxidation damage to wheat seedlings. Exogenous LaCl₃ could improve its antioxidant capacity by regulating the contents of antioxidant substances and the activities of antioxidant enzymes in wheat, thus resist the stress caused by heavy metal chromium and improve the anti-chromium property of wheat. 60 μmol/L LaCl₃ had the best effect, which could be used in production.