Abstract: Methylenetetrahydrofolate reductase(MTHFR) and methionine synthase reductase(MTRR) are the key enzymes in folate-methionine cycle, which play a vital role in the biological body and have been widely concerned. The polymorphisms of MTHFR C677T(rs1801133), A1298C(rs1801131), and MTRR A66G(rs1801394) may lead to alterations in the proteins they encode, which in turn lead to a decrease in the activity of the corresponding enzymes, affecting on the folate-methionine cycle, and causing an increase in the level of homocysteine and abnormal methylation level in vivo, contributing to the development of a variety of diseases. However, there are still some diseases with unclear pathogenesis. In this review, the research progress of MTHFR and MTRR genes and related diseases is reviewed, aiming to provide a new direction for the early screening and prevention of related diseases.