Cancer is a complex disease caused by the malignant cellular proliferation and metastasis. Elucidating its pathogenic mechanism is one of the major challenges that we face currently. Epigenetic mechanisms are essential for maintaining specific patterns of gene expression and normal development and growth of living individuals. Disorders of epigenetic markers, such as histone modification, DNA/RNA methylation, and changes in the three-dimensional conformation of chromatin, can interfere with gene expression to some extent, and result in cancers. This review provides a brief overview of epigenetics, focusing on their association with the genesis of cancers, and we look forward to the application of epigenetics in cancer clinical diagnosis and treatment.