The current study was carried out to assess the potential functions of exogenous glucose (Glu) on plant growth, nitrogen metabolism, and antioxidant defense system in cucumber seedings under salt stress. Our results revealed that the cucumber seedlings exposed to salinity for 7 d exhibited a significant reduction of plant height, and fresh and dry weight. The salt-induced growth inhibition was effectively alleviated by foliar application of 100 mmol L^-1 Glu. Exogenous Glu supplementation strikingly reduced the malondialdehyde content and controlled overaccumulation of superoxide anion () generation rate in the salt-stressed cucumber leaves. In addition, Glu significantly increased the antioxidant enzymes activities such as super oxidase dismutase, peroxidase, catalase and ascorbate peroxidase, and regulated gene expressions of encoding these enzymes, which decreased oxidative damage induced by salt stress. The content significantly decreased, but the level significantly increased due to salt treatment. However, Glu significantly increased the activities of nitrate reductase and nitrite reductase in salt-stressed cucumber leaves, which coincided with modulating the gene expressions of key enzymes of nitrogen metabolism, and thus, promoted the conversion of ammonium nitrogen to amino acids and proteins. These results suggest that exogenous Glu could alleviate salt-induced growth inhibition through regulating antioxidant capacity and nitrogen metabolism, which is associated with an improvement of cucumber growth and salt tolerance.