Abstract: A surfactant having the capacity of reducing the surface tension in pulmonary alveoli significantly is provided. The surfactant consists essentially of, based on the total weight of the surfactant, 50.6-85.0% of a chlorine phosphogylceride, 4.5-37.6% of an acid phospholipid, 4.6-24.6% of a fatty acid or its analogue and 0.1-10.0% of a lipoprotein derived from the lung of a mammal. These components cooperate to form a kind of film at a gas-liquid interface within pulmonary alveoli and reduce the surface tension. A pharmaceutical composition comprising the surfactant is useable for the clinical treatment of respiratory distress syndrome.