To investigate the role of candidate genes for salt-alkali tolerance in cucumber (Cucumis sativus L.), this study screened CsTAU1 in the glutathione pathway from previous transcriptome data for cloning and functional analysis. Clone cucumber CsTAU1 contains one 675 bp open reading frame, containing one GST-N-Tau domain and one GST-C-Tau domain, and is expressed in cytoplasm. After successfully constructing overexpression vectors of CsTAU1 (+) and CsTAU1 (-), they were transferred into cucumber varieties 'D1909' (high salt alkali resistance) and 'D1604' (low salt alkali resistance) for salt-alkali resistance identification. It was found that under salt-alkali stress, CsTAU1 (+)-overexpressing plants showed strong resistance to salt-alkali stress, while CsTAU1 (-)-overexpressing plants showed the opposite situation. qRT-PCR analysis was performed on other glutathione pathway-related genes in CsTAU1-overexpressing plants. The expression patterns of LOC101219529 and LOC105434443 were the same as CsTAU1, and the introduction of CsTAU1 (+) increased the chlorophyll, α-Naphthylamine oxidation, glutathione S-transferase (GST), and catalase (CAT) content of cucumber. The research results provide a theoretical basis for cultivating salt-alkali-tolerant cucumber varieties.