It is generally believed that platelets are cytoplasmic bodies with biological activity falling off the cytoplasm of megakaryocytes from bone marrow. However, a large number of megakaryocytes have been found in the lung tissue in many researches. Whether the lung has the function of producing platelets has been controversial. In this paper, we briefly review the proposition, early stage researches, the latest confirmations and possible meaning of the hypothesis of platelet-producing function of lung.