In this study, physiologicalbiochemical and histochemical approaches were applied to investigate the role of H₂S in salicylic acid (SA) alleviated Al stress in the root of SB (aluminum (Al)sensitive black soybean). The results showed that: (1) Al accumulation in black soybean (SB) roots was increased by AlCl₃ treatment and the cotreatment of AlCl₃ and SA could significantly inhibit the accumulation of Al. But after adding H₂S scavenger (HT) or H₂S synthesis inhibitor (PAG), the accumulation of Al in SB roots was aggravated. (2) SA increased endogenous H₂S levels of black soybean (SB) root by 1.5fold under Al stress, and significantly alleviated root growth inhibition, reactive oxygen species (ROS) accumulation, oxidative damage and cell death induced by Al stress. Cotreatment of HT or PAG significantly reduced endogenous H₂S level, and it can reverse the alleviation effect of all SA under Al stress. (3) SA reduced the activities of black soybean (SB) apical antioxidant enzyme CAT, SOD and APX under Al stress, and inhibited the production of ROS in SB root cells. Inhibition of H₂S signal by HT or PAG enhances antioxidant enzyme activities. (4) Under the condition of Al stress, SA can further upregulate the expression of a series of Al tolerancerelated genes, such as exclusion mechanismrelated genes (Alresponsive transcription factor, GmART1; citric acid synthase, GmCS; citric acid transporter, GmMATE) as well as internal Al tolerance mechanismrelated genes (malic acid transporter, GmAlMT; Al³⁺related transporters, GmAlS1 and GmNIP1； 2). Reduction of endogenous H₂S level by HT or PAG can reverse the regulation of SA expression on these genes. (5) SA can increase the secretion of citric acid from black soybean (SB) root under Al stress, and this effect can also be inhibited by addition of HT or PAG. The study found that H₂S acted as a downstream signaling of SA and participate in the regulation of black soybean (SB) response to Al stress, which might provide some novel scientific basis for understanding Altolerance signaling network in plants.