〔Abstract〕 Objective To explore the role of secreted frizzled-related protein 3(sFRP3), a regulator of the Wnt signaling pathway, in the activation and proliferation of murine cardiac fibroblasts(CFs). Methods Neonatal mice aged 1-3 days were obtained for surgical procedures to collect heart tissues. After digestion, CFs were isolated and cultured. Transforming growth factor-beta 1(TGF-β1) stimulation was used to induce activation and proliferation in CFs after they adhered to the culture dish. Once the model was confirmed, experimental and control groups were transfected with sFRP3 overexpression plasmids and empty plasmids for 24-48 hours. Expression levels of sFRP3, Periostin(POSTN), Type Ⅰ collagen(Collagen Ⅰ), and proliferating cell nuclear antigen(PCNA) were assessed at the molecular level using Western blot and qRT-PCR. Changes in cell proliferation capacity were examined using MTT, CCK-8, and EdU staining methods. Results In the TGF-β1-induced activation and proliferation model of CFs, compared to the control group, the model group exhibited decreased expression of sFRP3 protein and mRNA, while the expression of activation and proliferation-related proteins PCNA, POSTN, and Collagen Ⅰ was upregulated. Furthermore, in CFs overexpressing sFRP3 through plasmid transfection, the protein and mRNA expression of PCNA, POSTN, and Collagen Ⅰ decreased compared to the empty vector group. MTT, CCK-8, and EdU experiments indicated a significant decrease in the proliferative activity of CFs in the sFRP3 overexpression group compared to the empty vector group. Conclusion Overexpression of sFRP3 markedly inhibits the activation and proliferation of CFs, suggesting that sFRP3 may be a key gene involved in the regulation of CF activation and proliferation.