Background: Mesenchymal stem cells (MSCs) have been reported totreat acute lung injury (ALI) by modulating inflammation, maintaining lung structure, preserving lung function, and inhibitingepithelial cells apoptosis. The aim of thepresent study is to investigate whether MSCs enhance lung repair via keratinocyte growth factor (KGF) in Oleic acid (OA) induced ALI (OA-ALI). Methods: Rats were administered OA to induce ALI model. Then they were given intravenous injections of Phosphate Buffered Saline (PBS), dermal fibroblasts (DF), DF-CM, MSCs, and MSC-scondition medium (MSC-CM) respectively. The extent of lung injuryand lung function was assessed. A subsequent in vitro experiment was performed to examine the potential role of MSCs secretion in attenuating lung epithelial repairment using injured lung epithelial administered with involved MSCs, MSC-CM, KGF, HGF and TGF-beta. Results: Both MSCs and MSC-CM significantly improve lung function following OA-ALI. MSCs enhanced restoration of systemic oxygenation, reduced total lung water, decreased lung inflammation and histological lung injury and restored lung structure. These effects were not seen with dermalfibroblastsadministraion. In vitro experiment supported that, Keratinocyte growth factorimproved lung epithelial repair. Conclusions: MSCs ameliorated lung repair by KGF in OA-induced ALI.