Abstract: The alveolar capillary endothelial barrier is mainly composed of alveolar capillary endothelial cells and alveolar epithelial cells. The destruction of this barrier and the continuous infiltration of inflammatory cells have been considered to play an important role in the development of chronic obstructive pulmonary disease, acute lung injury, and idiopathic pulmonary fibrosis. Therefore, it is of great significance to understand the mechanism of alveolar capillary endothelial barrier regulation. Sphingosine 1-phosphate (S1P) is a bioactive sphingolipid metabolite produced by sphingosine kinase. A large number of studies have shown that S1P not only regulates immune cell transport, but also plays important roles in regulating cell apoptosis, vascular endothelial barrier, and alveolar epithelial barrier. S1P exerts different regulatory effects on alveolar capillary endothelial barrier by activating S1P1 and S1P3. Activation of S1P1 on the alveolar capillary endothelial cells by S1P mediates barrier protection, while the barrier can be broken when S1P3 is stimulated by S1P. S1P can also regulate alveolar epithelial barrier. By activating S1P3 on the alveolar epithelial cells, S1P leads to epithelial barrier damage, which makes interstitial proteins and body fluids infiltrate into alveolar space and causes pulmonary edema. Therefore, it may be a target for the treatment of lots of lung diseases by regulating the homeostasis of alveolar capillary endothelial barrier. This paper reviews the research advancement of S1P in alveolar capillary endothelial barrier regulation.