The proliferation and maturation of hair follicles in follicular papilla cells are predominantly governed by miRNAs, which significantly influence the cell cycle, apoptosis, and proliferation. miR-370-3p has been associated with several biological processes and targets SMAD4, a crucial component in hair follicle development. Tissue expression profiling revealed significant differences in miR-370-3p levels between skin tissues of the two sheep breeds in January and October, as well as between tissues of the Xinji fine-wool sheep and Small-tail Han sheep. SMAD4 exhibited significant differences in tissue-specific expression in the heart, spleen, skin, lungs, and muscles from Xinji fine-wool sheep and Small-tail Han sheep. Bioinformatics analysis and dual-luciferase reporter assays validated the regulatory interaction between miR-370-3p and SMAD4. CCK-8 experiments demonstrated that miR-370-3p’s targeting of SMAD4 suppressed cell growth. Cell cycle analysis demonstrated that miR-370-3p’s targeting of SMAD4 influenced the cell cycle. Annexin V-FITC/PI dual labeling demonstrated that miR-370-3p’s targeting of SMAD4 promoted cell apoptosis. RT-qPCR data demonstrated that miR-370-3p’s targeting of SMAD4 elevated the expression of JUN, c-MYC, and TCF7L2 while suppressing β-catenin expression. Western blot (WB) analysis demonstrated that miR-370-3p targeting of SMAD4 significantly promoted c-MYC expression while inhibiting CCND1, CCND2, and β-catenin expression. miR-370-3p and SMAD4 exhibit spatiotemporal expression differences in sheep skin tissues, with widespread expression across various tissues. Furthermore, it confirmed that miR-370-3p targets SMAD4 to inhibit follicular papilla cell proliferation, promote apoptosis, and influence the cell cycle.