The members of the miR-29 family play an important role in the process of viral infection. The sheep pox epidemic has hindered the development of the livestock industry worldwide. The aim of this study was to analyze the action mechanism of miR-29a during sheep pox virus (SPPV) infection. We found that during viral infection, miR-29a showed a trend of increasing, then decreasing, and then again increasing. It was determined that AKT3 was a target gene of miR-29a, and miR-29a might be involved in the PI3K-AKT signaling pathway. SPPV was able to inhibit cell proliferation and promote apoptosis, and miR-29a reversed the inhibition of cell proliferation by SPPV and the promotion of apoptosis. This study provides an experimental basis and theoretical foundation for the pathogenic mechanism of SPPV infection, as well as contributing to the proposal of new strategies for the development of anti-sheep-poxvirus drugs.