Acute lung injury (ALI) and acute respiratory distress syndrome (ARDS) are major causes of respiratory failure, but currently, no effective pharmacotherapy exists for these disorders. Alveolar macrophages play a critical role in both the acute/initial phase and chronic/resolving phase of ALI, rendering them a potential therapeutic target. Interleukin-4 (IL-4), a Th2 cytokine, not only directly inhibits the secretion of pro-inflammatory factors from macrophages but also drives macrophages to the anti-inflammatory and tissue remodeling M2 type. However, the short half-life of IL-4 in vivo hampers its effect on disease treatment. In this study, macrophages secreting IL-4 (M-IL-4) were established and used to treat ALI through pulmonary macrophage transplantation (PMT). The results showed that highly sustained levels of IL-4 and M2 macrophage markers were detected in mice lungs following pulmonary M-IL-4 transplantation. Furthermore, PMT improved the therapeutic effect by reducing lung inflammation, alleviating tissue injury, reducing alveolar macrophages necrotic cell death, and decreasing mortality in mice with ALI. These results suggest an efficient macrophage-based protein drug delivery strategy, and for the first time, prove the feasibility and efficacy of PMT in ALI treatment.