Long non-coding RNA (lncRNA) SNHG14 is previously found to be overexpressed in several types of cancers. However, the clinical significance and biological function of SNHG14 in non-small cell lung cancer (NSCLC) are still elusive. In the present study, we found that SNHG14 was aberrantly upregulated in NSCLC tissues from patients and cell lines compared to their normal counterparts. Increased SNHG14 expression was closely associated with aggressive tumor progression and poor clinical outcome of NSCLC patients. Knockdown of SNHG14 inhibited NSCLC cell proliferation through inducing cell cycle arrest and apoptosis, whereas SNHG14 overexpression exerted the opposite effects. Animal experiment further revealed that downregulated SNHG14 greatly inhibited NSCLC tumor growth in vivo. Further studies demonstrated that SNHG14 might serve as a competing endogenous RNA (ceRNA) by sponging miR-340 in NSCLC cells. Taken together, our study demonstrated that SNHG14/miR-340 axis might play a novel role in regulating the malignant behaviors of NSCLC, which provided a new potential diagnostic and therapeutic strategy for this malignant disease.