Using processed tomato KT7 as material, under hydroponic conditions, we investigated the effects of exogenous salicylic acid (SA, 0.15 mmol/L) and hydrogen sulfide (H₂S) donor sodium hydride (NaHS, 50 mmol/L) on osmotic regulation, reactive oxygen metabolism and rapid chlorophyll fluorescence of tomato seedlings under 150 mmol/L NaCl stress, to explore the synergistic effect of H₂S and SA signal molecules and the physiological mechanism of alleviating salt stress in processed tomato seedlings in practical production. The results showed that: (1) both the treatments and their combination treatments could effectively alleviate the NaCl stress injury of processed tomato seedlings. (2) Compared with salt stress treatment, exogenous SA and H₂S treatments increased chlorophyll content, leaf relative water content and proline content to varying degrees, while decreased malondialdehyde (MDA) content, electrolyte permeability and H₂O₂ content to varying degrees. (3) The MDA content, electrolyte permeability and H₂O₂ production rate of processing tomato seedlings decreased to the minimum under the combined treatment of exogenous 0.15 mmol/L SA and 50 mmol/L H₂S, while the proline content of seedlings in the combined treatment reached the maximum. The study found that exogenous SA and H₂S under salt stress of single or compound treatment can improve the salt resistance of processing tomato seedlings, and H₂S and SA distribution treatment has a certain degree of synergy, can reduce the water loss of processing tomato leaf, induced seedling increased osmotic regulation ability, make seedling remains relatively complete the photosynthetic structure and strong vitality. Furthermore, the adaptability of processing tomato seedlings to salt stress was improved, indicating that H₂S and SA had mutual regulation mechanism in alleviating salt stress injury of processing tomato.