Objective To investigate the expression of microRNA-128a (miR-128a) in non-small cell lung cancer （NSCLC） tissues and its effects on proliferation and migration of NSCLC cells. Methods The miR-128a expression in NSCLC and normal lung tissues was determined by Real-Time PCR. The effects of miR-128a on proliferation and migration of NSCLC cells were tested by MTT assay, Transwell assay, and soft-agar assay with A549 cells transfected with miR-128a mimics and H1299 cells transfected with miR-128a inhibitor. Results The expression level of miR-128a was significantly down-regulated in NSCLC tissues than that in normal lung tissues. Overexpression of miR-128a could inhibit proliferation, migration, and colony formation of A549 cells. And down-regulation of miR-128a in H1299 cells could promote proliferation, migration, and colony formation. Conclusion The expression of miR-128a is down-regulated in NSCLC tissues, and miR-128a plays an important role in the initiation and development of NSCLC.