Background: The ATP-binding cassette (ABC) G subfamily, a key member of the ABC protein family, mediates plant stress responses by transporting metabolites across membranes, but its mechanism of action in tomato (Solanum lycopersicum L.) remains poorly understood. Methods: We systematically analyzed the evolutionary relationships, structural characteristics, stress-responsive expression patterns, and functional roles in response to saline-alkali stress of the SlABCG gene family in tomato, using a combination of approaches including phylogenetic analysis (MEGA), gene structure and motif analysis (GSDS, MEME), cis-acting element prediction, homology analysis, transcriptome analysis, protein-protein interaction prediction, and qRT-PCR validation. Results: We identified a total of 41 SlABCG genes from the tomato genome. These genes, together with 43 ABCG genes from Arabidopsis thaliana, were clustered into five distinct clades. There are 35 collinear gene pairs between the SlABCG gene family in tomato and the ABCG gene family in Arabidopsis, while 39 collinear gene pairs exist among ABCG genes within the tomato genome itself.The promoter regions of SlABCG genes contain cis-acting elements associated with responses to salicylic acid, low temperature, and gibberellin stresses. Transcriptome sequencing revealed that six SlABCG genes responded to saline-alkali stress. Gene regulatory network prediction revealed that multiple genes related to saline-alkali stress were regulated. Expression profile analysis of the 25 upregulated genes revealed that all of them were significantly upregulated during the saline-alkali stress treatment. Conclusions: In summary, our results provide deep insights into the characteristics of the SlABCG subfamily, facilitate the design of effective analysis strategies, and offer data support for exploring the roles of ABCG transporters under different stress conditions.