Objective To explore the mechanism of long non-coding RNA fibroblast activation inhibitory factor 1 (FAIF1) regulates the proliferation, activation, and fibrosis of human cardiac fibroblasts induced by advanced glycation end products (AGEs). Methods Human cardiac fibroblasts were assigned to control group, AGE group, FAIF1 recombinant lentivirus (Lv-FAIF1)＋AGE group or control lentivirus (Lv control)＋AGE group. The expression levels of miRNA-424-5p, FAIF1, and Smad7 in myocardial fibroblasts induced by AGEs were detected by quantitative polymerase chain reaction (qPCR) and Western blotting. Bioinformatics analysis was used to predict the interactions between miRNA-424-5p, FAIF1, and Smad7; and luciferase reporter assays were used for verification. Cell proliferation activity was measured by cell counting kit 8 assay, the expression and secretion of collagen Ⅰ/Ⅲ were observed by immunofluorescence staining, and the effect of Lv-FAIF1 on cell activation markers α-smooth muscle actin (α-SMA) and migration proteins matrix metalloproteinase 9 (MMP9) induced by AGEs was evaluated by qPCR. Results qPCR and Western blotting results showed that AGEs significantly reduced the expression of FAIF1 and Smad7 in myocardial fibroblasts and upregulated the level of miRNA-424-5p (compared with the control group, all P＜0.05). Bioinformatics analysis revealed that the 3'-untranslated region of Smad7 mRNA contained a binding site for the miRNA-424-5p seed sequence “UGCUGCU”, and FAIF1 sequence contained 3 identical binding sites. Luciferase assays showed that miRNA-424-5p inhibited the expression of Smad7, while FAIF1 competed with miRNA-424-5p for binding, thereby relieving the inhibitory effect of miRNA-424-5p on Smad7 mRNA. Functional experiments showed that Lv-FAIF1 significantly inhibited AGEs-induced cell proliferation, collagenⅠ/Ⅲ expression and secretion, as well as α-SMA and MMP9 expression (compared with AGE group, all P＜0.01); and it promoted the expression of Smad7 (compared with AGE group, P＜0.01). Conclusion miRNA-424-5p can inhibit the expression of Smad7, and FAIF1 effectively suppresses AGEs-induced over-activation of cardiac fibroblasts by regulating the miRNA-424-5p/Smad7 axis, which provides a new molecular target for the prevention and treatment of diabetic cardiomyopathy.