Abstract: Microsomal epoxy hydrolase(EPHX1) is an evolutionary highly conserved bioconvertase. The genetic code suggests that it has genetic polymorphism. Therefore, the EPHX1 gene has a variety of single nucleotide polymorphism(SNP), which there are two common SNP(rs1051740 and rs2234922) and lead to changes in enzyme activity. EPHX1 also has a wide range of substrate selectivity in function. It can biologically activate a variety of substrates, such as cholesterol, and participate in the metabolism of heterologous substances to achieve detoxification. It can also activate the carcinogenicity of polycyclic aromatic hydrocarbons through catalysisto induce cancer. Therefore, EPHX1 gene structure, distribution, polymorphism, and physiological function are related to multiple human diseases. This article will summarize the key points of EPHX1 gene and related diseases, then provide reference for further research of EPHX1 gene.