〔Abstract〕 Objective To explore the effect of YTH domain family protein 1(YTHDF1) on the activation, proliferation and migration of hepatic stellate cells(HSCs) by regulating mitochondrial fission mediated by mitochondrial fission protein 1(Fis1). Methods The mouse hepatic stellate cell line JS-1 was treated with 5 ng/ml TGF-β1 for 24 h to induce its activation and proliferation, andYTHDF1-siRNA was used to construct aYTHDF1silencing model.The experiment was divided into Control group, TGF-β1 group, TGF-β1+si-NC group and TGF-β1+si-YTHDF1 group.Expression changes ofYTHDF1,Fis1and key indicators of fibrosis, type Ⅰ collagen(CollagenⅠ) and α-smooth muscle actin(α-SMA) were detected through reverse transcription quantitative polymerase chain reaction(RT-qPCR) and Western blot; CCK-8 was used to detect cell proliferation ability; Transwell migration assay and cell scratch assay were used to detect cell migration ability; immunofluorescence staining experiment was used to detect the effect ofYTHDF1onFis1-mediated mitochondrial fission; finally, JC-1 staining was used to experimentally detect the effect ofYTHDF1on mitochondrial membrane potential. Results Compared with the Control group, RT-qPCR and Western blot experimental results showed that the expression ofYTHDF1andFis1increased in the TGF-β1 group(P<0.05,P<0.01;P<0.000 1), as well as the fibrosis markersCollagenⅠand the expression level of α-SMA increased(P<0.01;P<0.001,P<0.000 1); while adding CCK-8, the experimental results showed that the proliferation ability of HSCs in the TGF-β1 group was enhanced(P<0.000 1); Transwell experimental results showed that the migration ability of HSCs in the TGF-β1 group was enhanced(P<0.01); the cell scratch experiment results showed that the migration ability of HSCs in the TGF-β1 group was enhanced(P<0.000 1); the immunofluorescence experiment results showed that the TGF-β1 group Mito-Tracker Red staining andFis1co-localization signal increased(P<0.05); JC-1 staining experiment results showed that the mitochondrial membrane potential increased in the TGF-β1 group(P<0.01). Compared with the TGF-β1+si-NC group, RT-qPCR and Western blot experimental results showed that the expression ofYTHDF1andFis1in the TGF-β1+si-YTHDF1 group was reduced(P<0.01;P<0.001), and fibrosis markers the levels ofCollagenⅠandα-SMAwere reduced(P<0.01;P<0.001,P<0.01).CCK-8 experimental results showed that the proliferation ability of HSCs in the TGF-β1+si-YTHDF1 group was weakened(P<0.000 1); Transwell experiment results showed that the migration ability of HSCs in the TGF-β1+si-YTHDF1 group was weakened(P<0.001); cell scratch experiment results showed that the migration ability of HSCs in the TGF-β1+si-YTHDF1 group was weakened(P<0.000 1); immunofluorescence experiment results showed that the Mito-Tracker Red staining andFis1co-localization signal decreased in the TGF-β1+si-YTHDF1 group(P<0.01); JC-1 staining experiment results showed that mitochondrial membrane potential decreased in the TGF-β1+si-YTHDF1 group(P<0.05). Conclusion YTHDF1promotes the activation, proliferation and migration capabilities of HSCs by positively regulatingFis1-mediated mitochondrial fission. This suggests thatYTHDF1may be a key gene involved in regulating the activation, proliferation and migration of HSCs.