Objective: To investigate the expression and action of LncRNA SNHG15 in thyroid cancer cells. Methods: The LncRNA SNHG15 expressions in human undifferentiated thyroid carcinoma FRO cells, thyroid squamous cell carcinoma SW579 cells and human thyroid ductal carcinoma TT cells as well as normal thyroid HT-ori3 cells were determined by qRT-PCR. In FRO cells after transfection with SNHG15 siRNA or negative control siRNA sequences, the cell proliferation was tested by CCK8 assay and colony-forming assay, the cell apoptosis was measured by flow cytometry, and the expression levels of apoptosis-related protein were analyzed by Western blot, respectively. Results: The expression levels of LncRNA SNHG15 in FRO, SW579 and TT cells were all significantly higher than that in HT-ori3 cells, with the highest level in PRO cells (all P<0.05). In FRO cells transfected with SNHG15 siRNA compared with those transfected with negative control sequences, the proliferative and colony-forming abilities were significantly decreased, apoptosis rate was significantly increased, and the protein expressions of caspase-3 and Bax were up-regulated, while Bcl-2 protein expression was down-regulated significantly (all P<0.05). Conclusion: LncRNA SNHG15 expression is increased in thyroid cancer cells, and moreover, the poorer the differentiation of the cells, the higher is the expression of LncRNA SNHG15. LncRNA SNHG15 silencing can inhibit proliferation and promote apoptosis of thyroid cancer cells.