An excessive proliferation of skin fibroblasts usually results in different skin fibrotic diseases. Hydrogen sulphide (H₂S) is regarded as an important endogenous gasotransmitter with various functions. The study aimed to investigate the roles and mechanisms of H₂S on primary mice skin fibroblasts proliferation. Cell proliferation and collagen synthesis were assessed with the expression of α-smooth muscle actin (α-SMA), proliferating cell nuclear antigen (PCNA), Collagen I and Collagen III. The degree of oxidative stress was evaluated by dihydroethidium (DHE) and MitoSOX staining. Mitochondrial membrane potential (ΔΨm) was detected by JC-1 staining. Necroptosis was evaluated with TDT-mediated dUTP nick end labelling (TUNEL) and expression of receptor-interacting protein kinase 1 (RIPK1), RIPK3 and mixed lineage kinase domain-like protein (MLKL). The present study found that α-SMA, PCNA, Collagen I and Collagen III expression were increased, oxidative stress was promoted, ΔΨm was impaired and positive rate of TUNEL staining, RIPK1 and RIPK3 expression as well as MLKL phosphorylation were all enhanced in skin fibroblasts from cystathionine γ-lyase (CSE) knockout (KO) mice or transforming growth factor-β₁ (TGF-β_1, 10 ng/mL)-stimulated mice skin fibroblasts, which was restored by exogenous sodium hydrosulphide (NaHS, 50 μmol/L). In conclusion, endogenous H₂S production impairment in CSE-deficient mice accelerated skin fibroblasts proliferation via promoted necroptosis, which was attenuated by exogenous H₂S. Exogenous H₂S supplement alleviated proliferation of skin fibroblasts with TGF-β₁ stimulation via necroptosis inhibition. This study provides evidence for H₂S as a candidate agent to prevent and treat skin fibrotic diseases.