Recently, long noncoding RNAs (lncRNAs) have been shown to be linked to regulate different biological processes, such as cell growth, differentiation and tumorigenesis. LncRNAs have been identified to be promising clinical biomarkers in various tumors. Long noncoding RNAs cancer susceptibility candidate 2 (CASC2) has recently been demonstrated to be correlated to tumorigenesis in renal cell carcinoma, lung carcinoma, glioma, and gastric carcinoma. Nevertheless, the research on the biological function and clinical significance of CASC2 in thyroid carcinoma are still unclear. In this research, we focused on the relationship between CASC2 expression and clinicopathological factors in thyroid cancer. We found that the low expression of CASC2 correlated with multifocality and advanced tumor-node-metastasis (TNM) stage. Kaplan-Meier survival analysis and multivariate analysis showed that CASC2 expression may be an independent prognostic factor in human thyroid carcinoma. Moreover, the area under the receiver operating characteristic (ROC) curve of CASC2 indicated that its diagnostic value in thyroid carcinoma. Additionally, overexpression of CASC2 significantly inhibited the proliferation of thyroid carcinoma cells and arrested cell cycle at G0/G1 stage in thyroid cancer cells. Our findings showed that CASC2 may be a potential prognostic marker and therapeutic target.