Epigenetic, which refers to heritable differences of genes without changing their DNA sequences, is one of the most important biology phenomena in multicellular eukaryotes. Its research contents involves DNA methylation, genomic imprinting, histone acetylation, histone methylation, chromatin remodeling, pseudogene, and microRNA etc. Monozygotic twins is developed from one single zygote and are genetically identical in genomic DNA sequence. From the view of classical genetics, traditional genetic markers such as short tandem repeat and single nucleotide polymorphism can not play important role in discriminating monozygotic twins. So it is very essential to find new genetic markers. Recent achievements made in epigenetics show that there exist striking differences in monozygotic twins and provide a new strategy to discriminate the monozygotic twins. In this paper, the concepts, research contents of epigenetics and its application perspective in discriminating monozygotic twins are reviewed.