Prostaglindin E1 (PGE1) is an auto active compound and a product of arachidonic acid, which plays an important role in inflammatory reaction and immunologic reaction. Severe pneumonia is acute damage of lung parenchyma caused by multitude cytokine mediators of inflammation. PGE1 inhibits the gather and activation of polymorphonuclear neutrophils in the lung, impacts pulmonary hemodynamics, regulates pulmonary respiratory function, has an effect on cytokines and oxidation or anti-oxidation system, restrains the expression and release of inflammatory cytokines,adjusts immune cells in apoptosis. All of the above are important mechanism in the treatment of severe pneumonia. The article summarizes the studies on PGE1 and related views.