Abstract: With the development of tumor research, it is found that of epigenetic alterations are also closely related with the development and progression of tumors besides gene mutations. The change of tumor epigenetic inheritance are mainly presented as the aberrant methylation of DNA. The aberrant methylation of DNA occurs in almost all kinds of human tumors, including cutaneous malignancies. DNA methylation refers to the process that under the effect of DNA methylase, methyl is transferred onto a special basic group with S- adenosine-L-methionine （SAM）as the methyl donor. The normal function of gene not only depends on a normal structure, but also depends on a normal state of methylation. The aberrant methylation of DNA takes an important part in the occurrence of tumor.