Background: The serum levels of sclerostin (SOST) are significant elevated in patients with pathological cardiac remodeling after myocardial infarction (MI). However, the mechanisms of SOST in cardiac remodeling remain largely uncharacterized. Methods: Collecting patients with MI who presented with or without left ventricular (LV) remodeling, we investigated differences in SOST expression. The influence of overexpression and silenced of SOST on the angiogenesis of cardiac microvascular endothelial cells (CMECs) was explored through in vitro experiments, and the impact of SOST on Wnt signaling marker proteins was examined by quantitative reverse transcription-polymerase chain reaction (qRT-PCR) and Western blot. Finally, we observed the effects of SOST on cardiac function and morphology in mice MI model, and verified the role of the Wnt signaling marker proteins in vivo. Results: Serum SOST was significantly increased in patients with cardiac remodeling. Increased SOST expression was also observed in the infarcted hearts of C57BL/6 mice that underwent ligation of the left anterior descending branch of the coronary artery to induce MI. Furthermore, loss and gain of function experiments were conducted to investigate the role of SOST in post-infarct cardiac remodeling in vivo and in vitro. Overexpression of SOST promoted the proliferation and migration of cardiac fibroblasts (CFs), and inhibited angiogenesis of CMECs. In addition, overexpressing SOST in mice significantly deteriorated the post-infarct cardiac remodeling, as shown by the increased LV end systolic and end diastolic dimensions, decreased ejection fraction, and increased myocyte cross-section area and myocardial fibrosis. However, suppressing SOST expression showed the opposite results. The expression of Wnt signaling marker proteins was inhibited after overexpression of SOST, and enhanced after suppression of SOST in vivo and in vitro, suggesting involvement of the Wnt signaling pathway. Conclusions: The present study demonstrated that SOST aggravates post-infarct pathological myocardial remodeling by inhibiting angiogenesis of CMECs while promoting the proliferation of CFs, and this may be mediated by the Wnt signaling pathway. These results suggested that SOST might act as a biomarker to predict detrimental postinfarct cardiac remodeling, and may be a potential therapeutic target for the treatment of MI.