We have summarized increasing data from all kinds of experiment results of papers in recent years, which are associated with tumor suppressor genes, oncogenes, and thyroid-specific genes and attempt to elucidate the importance of epigenetic modifications and the mechanisms of aberrant DNA methylation in thyroid cancer in this review. The results showed that current articles have revealed the importance of epigenetic modifications and the different types of mechanisms in thyroid cancer. The mechanisms of DNA methylation related to thyroid cancer demonstrate that acquired epigenetic abnormalities together with genetic changes play an important role in alteration of gene expression patterns. Aberrant DNA methylation has been well known in the CpG regions. Among the genes identified, we have shown the status of DNA promoter methylation in papillary, follicular, medullary, and anaplastic thyroid cancer. It suggested that thyroid cancer subtypes present differential promoter methylation signatures, which will encourage potential thyroid cancer detection in its early stages, assessment of prognosis, and targeted cancer treatment.