Objective: To investigate the effect of microRNA (miR)-411 on proliferation and invasion of thyroid cancer cells and its mechanism. Methods: The expression of miR-411 in 100 thyroid cancer tissues and 3 thyroid cancer cell lines SW579, TPC-1 and FTC-133 were detected by real-time fluorescence quantitative PCR, and the relationship between the expression of miR-411 and the clinicopathological characteristics of thyroid cancer patients was analyzed. The cultured TPC-1 cells were divided into an untransfected group, a negative control group (NC) and a miR-411 group. After transfection of miR-411 mimic and its negative control, the expression of miR-411 was detected by real-time fluorescence quantitative PCR, the proliferation and invasion of cells in each group were detected by methylthiazolyldiphenyl-tetrazolium bromide (MTT) assay and Transwell chamber, respectively. Results: Compared with the adjacent tissues, the expression of miR-411 in thyroid cancer tissues was significantly lower (P<0.05), and the expression of miR-411 was related to tumor size, TNM stage, and lymph node metastasis (P<0.05), but not to gender and age (P>0.05). Compared with the normal human thyroid cell line Nthy-ori 3-1, the expression of miR-411 in SW579, TPC-1, and FTC-133 cells was significantly lower (P<0.05), and the expression of miR-411 in TPC-1 cells was the lowest. There was no significant difference in the expression level of miR-411, proliferation activity and number of invasive cells between the non-transfected group and the NC group (P>0.05). Compared with the non-transfected group or the NC group, the expression level of miR-411 increased significantly, while the proliferation activity and number of invasive cells decreased significantly in the miR-411 group (P<0.05). Conclusion: The expression of miR-411 is low in thyroid cancer. Upregulation of miR-411 expression can inhibit cell proliferation and invasion.