Tetraspanin protein CD151 is overexpressed in a wide variety of cancer types, including lung cancer, and is closely associated with metastasis and poor prognosis of carcinoma. To investigate whether knockdown of CD151 expression can inhibit the malignant biological behavior of lung adenocarcinoma (LAC), RNA interference technology (RNAi) was used to silence CD151 expression in the A549 LAC cell line. Specific small interfering RNA (siRNA) for targeting human endogenous CD151 were delivered into A549 cells in order to examine the effects on cell proliferation, survival, migration, invasion and colony formation. The expression levels of CD151 were assayed by western blotting, proliferation was evaluated by MTT method and apoptosis was determined by flow cytometry. The invasive and metastatic ability of A549 cells was investigated by wound healing and Boyden chamber assays. Colony formation analysis was used to determine the A549 cell growth properties. Finally, the expression of phosphorylated FAK, PI3K-AKT, MEK-Erk1/2, MMPs, and VEGF was detected by western blotting. The results demonstrated that CD151-siRNA significantly decreased the expression level of CD151 in A549 cells. Reduced CD151 expression in A549 cells lead to the inhibition of cellular proliferation, migration, invasion and colony formation and an enhancement of apoptosis. Furthermore, the expression of tumor development-related proteins, including FAK, PI3K-AKT, MEK-ERK1/2MAPK as well as the expression of MMP9 and VEGF, were restrained. Taken together, the present study has shown that CD151 expression is essential for LAC progression. Thus, knockdown CD151 expression by targeted siRNA could inhibit the related downstream intercellular signaling pathways, and this way provide a novel gene therapy for patients with LAC.