Abstract: Objective To study the polymorphisms of methylenetetrahydrofolate reductase (MTHFR) gene and its relationship with hypertension. Methods From January to November in 2017,187 patients received cardiovascular medical treatment in our center,including 69 cases of hyperhomocysteinemia (HHcy group) and 118 cases with normal blood homocysteine (Nor-Hcy group),were enrolled in this study.The MTHFR gene polymorphism was detected by polymerase chain reaction (PCR)-chip hybridization technique,and the genotype distribution of MTHFR and the association of C677T mutation with occurrence of HHcy and hypertension were analyzed. Results Compared with the Nor-Hcy group,the HHcy group had more male patients (88.4% vs 72.9%,P=0.012) and higher prevalence of hypertension (85.5% vs 73.7%,P=0.043).TT was the most common genotype of MTHFR in the HHcy group,and it was significantly higher than that of the Nor-Hcy group (73.9% vs 22.0%,P<0.001),and so was the proportion of t carriers (84.78% vs 50.0%,P<0.001).Moreover,proportions of TT genotype and t carrier were significantly higher in patients with H-type hypertension (hypertension combined with HHcy) compared with the non H-type hypertension group (P<0.001).Theproportion of CT+TT genotypes in patients with H-type hypertension was significantly higher than that in the non H-type hyper-tension group,which might increase the risk of HHcy (odds ration,OR=6.22) and H-type hypertension (OR=5.57). Conclusion CT+TT mutations in the C677T loci of the MTHFR gene is associated with higher risk of HHcy and H-type hypertension.