Abstract: Objective To identify the miR-663 targeted gene TGFB1 using a dual fluorescent protein reporter assay system and to reveal the possible mechanism of miR-663 to promote the proliferation of A549 lung cancer cells. Methods The expression of miR-663 in lung cancer in 10 pairs of lung cancer tissues and in their adjacent normal tissues was measured using microRNA specific qRT-PCR.Than the effects of miR-663 on the proliferation of A549 cells transfected by miR-663 LNA (locked nucleic acid) was analyzed by cell growth curve and colony formation assay.A sequence of TGFB1 3′UTR(untranslated region) was inserted into the plasmid which expressed green fluorescent protein (pcDNA3/EGFP).This plasmid (pcDNA3/EGFP- TGFB1 3′UTR) and miR-663 and the plasmid expressed red fluorescent protein (pDsRed2 -N1) were cotransfected into A549 cells.The cells and the extracted protein had been detected under fluorescence microscope and the fluorescence spectrophotometer respectively. Results MiR-663 was highly expressed in lung cancer tissues and A549 cells.Decreased level of miR-663 could significantly inhibit the proliferation of lung cancer cells.After miR-663 and the plasmid of pcDNA3/EGFP- TGFB1 3 ′UTR being cotransfected,the intensity of green fluorescent protein was significantly lower than that in the group of cotransfected pcDNA3/EGFP- TGFB1 3′UTR with pcDNA3. Conclusion This study demonstrated that miR-663 contributes to A549 cell proliferation through direct regulating of the expression of TGFB1 directly.