To investigate the morphological changes in the facial muscle (specifically, the levator nasolabial muscle) and differences in the expression of contraction-related proteins α-actin and α-actinin following two months of denervation due to facial nerve injury in rats, aiming to elucidate the pathological mechanisms underlying facial muscle atrophy and functional decline post-denervation. Methods: Twenty healthy adult Sprague-Dawley (SD) rats were used. A model of denervation was established by transecting the main trunk of the left facial nerve at its exit from the stylomastoid foramen, while on the right side, only exposure of the facial nerve via an identical surgical approach served as the control. Two months after surgery, bilateral levator nasolabial muscles were harvested for analysis. Wet weights were measured, Masson's trichrome staining was performed to assess myofiber morphology and collagen fiber proliferation, and immunohistochemical staining was employed to detect the expression levels of α-actin and α-actinin. Results: The wet weight of the denervated (lesioned) side was significantly lower than that of the control side (P<0.05). Masson's staining revealed reduced number, diameter, and cross-sectional area of myofibers, along with significantly increased collagen deposition on the lesioned side (all P<0.05). Immunohistochemistry showed a marked decrease in α-actin expression on the denervated side (P<0.05), whereas no statistically significant difference in α-actinin expression was observed between the two sides (P>0.05). Conclusion: After two months of facial nerve transection, rats exhibited obvious facial muscle atrophy, enhanced collagen fibrosis, and downregulated expression of the contractile protein α-actin, indicating structural degeneration and impaired contractile function induced by denervation. Future studies should conduct staged observations and refine experimental methodologies to further uncover the underlying mechanisms and explore potential therapeutic strategies.