Our study aspires to understand the impact of miR-27b on myocardial fibrosis as well as its functional mechanism. 12 days post the ligation of coronary artery in rats, the expression of miR-27b in the peri-infarction region was elevated. Treating cultivated rat neonatal cardiac fibroblasts (CFs) with angiotensin II (AngII) also enhanced the miR-27b expression. Forced expression of miR-27b promoted the proliferation and collagen production in rat neonatal CFs, as revealed by cell counting, MTT assay, and quantitative reverse transcription-polymerase chain reaction. FBW7 was found to be the miR-27b's target since the overexpression of miR-27b reduced the transcriptional level of FBW7. The enhanced expression of FBW7 protein abrogated the effects of miR-27b in cultured CFs, while the siRNA silence of FBW7 promoted the pro-fibrosis activity of AngII. As to the mechanism, we found that the expression of FBW7 led to the degradation of Snail, which is an important regulator of cardiac epithelial-mesenchymal transitions. Importantly, inhibition of miR-27b abrogated the coronary artery ligation (CAL) induced cardiac fibrosis in vivo, suggesting that it might be a potential target for the treatment of fibrosis associated cardiac diseases.