Increasing evidence has shown that microRNA (miRNA) is extensively involved in the pathophysiology of lung cancer. Microarray data demonstrated the increasing levels of miR-19a in the peripheral blood from patients suffering from lung cancer, which is closely associated with poor prognosis of lung cancer. However, the underlying molecular mechanism of miR-19a remains to be determined. The results of the present study showed a higher expression of miR-19a compared with normal bronchial epithelial cells. Furthermore, lentivirus vectors were constructed to establish cell lines that over-expressed and knocked out miR-19a in order to study the role of miR-19a on the metastasis and proliferation of lung cancer cells. Investigation into the underlying mechanism of miR-19a, revealed that MXD1 may be the key gene targeting miR-19a, participating in the process of proliferation and metastasis of lung cancer cells.