The etiology and underlying biological mechanisms for preterm birth are relatively intricate, involving both genetic and environmental factors. Therefore, in the process of research on environmental factors of preterm birth, individual genetic susceptibility is an important aspect which cannot be ignored. Detoxification and metabolism abilities of enzymes to the environmental toxins is determined by their genetic polymorphism, which directly affect the toxic effects of poison. The measurement of gene polymorphisms related to metabolic enzymes may have important significance in the research of biological mechanisms, the risk prediction for preterm birth and the development of the preventive measures. In the recent studies, exposure to polycyclic aromatic hydrocarbons (PAH) seems to be an important risk factor for preterm birth. Cytochrome P450 (CYP450s) and glutathione S-transferases (GSTs) are the main metabolic enzymes of PAH and many other xenobiotics, and the polymorphisms of CYP1A1, CYP2E1, GSTM1, GSTT1 and GSTT2 may be associated with the risk of preterm birth. In this paper, we summarized that the research progress on the relationship between the gene polymorphisms of metabolic enzyme related to PAH and the risk of preterm birth.