DHE, MitoSOX, and JC-1 staining in our experiment confirmed that NaHS pretreatment decreased intracellular superoxide anion and mitochondrial superoxide but increased mitochondrial membrane potential in keloid fibroblasts and TGF-β1-stimulated normal skin fibroblasts, suggesting that exogenous H2S supplementation attenuated oxidative stress. Here, TGFB1 is linked to keloid.