Abstract: In order to understand the molecular mechanism of sweet sorghum related to its adaptation to soda saline-alkali stress at the protein level, the variety M-81E, which has better tolerance to soda salinealkali stress, was selected as the material. Various proteins were identified by twodimensional electrophoresis and mass spectrometry together with the bioinformatics analysis. Dynamic changes of antioxidant enzyme activities in M81E were detected under soda salinealkali stress. Among the identified 44 proteins, 30 and 14 showed up and downregulated expressions, respectively, which were mainly related to the biological processes of material and energy metabolism, signal transduction and transcription regulation. Gene ontology analysis showed that the differential proteins were mainly involved in redox biological processes. KEGG enrichment analysis showed that the differential proteins were significantly involved in metabolic pathways such as carbon metabolism, carbon fixation in photosynthetic organisms, glycolysis and biosynthesis of secondary metabolites. The network of proteinprotein interaction showed that proteins interacted with each other and directly or indirectly involved in the metabolic pathway. Compared with the control, SOD and CAT activities were significantly decreased (P<0.05) after soda salinealkali treatment for 4 hours and GSHPx activity was not significantly changed, while POD activity increased significantly (P<0.01) in the sweet sorghum seedlings. Correspondingly, the contents of MDA and H₂O₂ in the treated group were lower than those in the control (P<0.01). POD could be the key enzyme to scavenge ROS in sweet sorghum at the early stage of soda salinealkali stress. The activities of various antioxidant enzymes decreased differently after 16 h treatment, and were still higher than the control after 24 h treatment but the contents of MDA and H₂O₂ increased sharply.