Influenza A virus infection can cause acute respiratory distress syndrome (ARDS), and to date, viral pneumonia has been the main cause of ARDS. Bone marrow mesenchymal stem cells have shown promise for treating lung injury caused by avian influenza virus infection. At present, studies of the use of other stem cell types to treat human influenza virus-mediated lung damage are sparse. We assessed the use of umbilical cord mesenchymal stem cells (UC-MSCs) to treat damage from serious H1N1 influenza virus infections in cell and animal-based experiments. Maximum viral titers, inflammatory factor expression levels, differential expression of alveolar cell-related proteins, animal weight and survival rate, lung histopathology, and other indicators were evaluated. Compared with the control group, in cellular experiments, UC-MSCs could effectively inhibit H1N1 influenza viral replication and repair damaged host cells. In animal experiments, UC-MSCs reduced expression of pro-inflammatory cytokines, reduced entry of inflammatory cells into the lungs, alleviated lung inflammation, significantly reduced the extent of lung injury in mice, and improved lung histopathology, improving overall survival. A positive role of umbilical cord-derived mesenchymal stem cells in treating lung injury caused by H1N1 influenza virus infection that is worthy of clinical promotion has been demonstrated.