The objective of this work was to elucidate the effect of exogenous H₂S on cucumber protein expression under high salt stress. The saltsensitive cucumber cultivar ‘Chunxiaqiuwang’ was used as experimental material. The leaf proteins were separated by twodimensional electrophoresis (2DE), and the differential proteins were identified by matrixassisted laser desorption ionization tandem timeofflight/timeofflight mass spectrometry (MALDITOF/TOFMS). Functional annotation and metabolic pathway analysis of differentially expressed proteins were performed using NCBI and SwissProt database searches. The results showed: (1) about 2 490 protein spots were detected, of which 45 were differentially expressed at 1.5fold and P < 0.05 levels.The 24 proteins were upregulated, and 21 proteins were downregulated. (2) 26 proteins were successfully identified. These proteins are involved in photosynthesis (26.92%), protein metabolism (23.07%), energy and carbohydrate metabolism (11.54%), amino acid biosynthesis (11.54%), cell structure related protein (7.69%), antioxidant reaction (3.85%), signal transduction (3.85%) and unknown functional protein (11.54%). (3) The GO annotation showed that many differential expressed proteins is mainly composed of protein binding and hydrolase activity in molecular function, distributed in response to stimulus, organic substance metabolic process, response to stress and cell differentiation etc. in biological process, cell part and intracellular organelle in cellular component. KEGG metabolic pathway analysis showed that differential proteins are mainly involved in actin cytoskeleton regulation, apoptosis, carbon metabolism and light and regulation. The research indicated that exogenous H₂S induced differential expression of cucumber leaf protein under high salt stress, which provided a theoretical basis for the subsequent exploration of exogenous H₂S on the saltresistant molecular mechanism of cucumber.