AIM: To investigate the distribution characteristics of methylenetetrahydrofolate reductase (MTHFR) gene polymorphism and its correlation with blood Hcy in hypertensive patients and to provide reference for the prevention and treatment of H-type hypertension in southern Anhui Province. METHODS: A total of 657 hypertensive patients were treated in our hospital from October 2019 to August 2020 were selected as the research objects. The MTHFR C677T and A1298C loci were genotyped by fluorescence staining in situ hybridization, and the blood Hcy concentration was determined by the enzyme cycle method. The distribution characteristics of MTHFR gene in the Han nationality hypertensive population in southern Anhui Province were analyzed, and compared with the reported MTHFR gene distribution data of hypertensive populations in other regions and ethnic groups. RESULTS: Among the 657 patients, the distributions of CC, CT and TT types at the C677T site of MTHFR gene were 212(32.27%), 321 (48.86%), 124(18.87%), and the distribution of AA, AC, and TT types at the A1298C site were 467 (71.08%), 171(26.03%), 19(2.89%). There was no gender difference in the distribution of the two loci of this gene in the hypertensive population in southern Anhui Province (P > 0.05). The distribution frequency of CC genotype at C677T locus is lower than that in Foshan and Guangxi, but higher than that in Henan, Xinjiang and Inner Mongolia; the frequency of CT genotype is higher than that in Foshan and Guangxi; the frequency of TT genotype is higher than that in Foshan and Guangxi. Guangxi region was lower than Henan region, Xinjiang region and Inner Mongolia region, and the difference was statistically significant (P < 0.05). The mean blood Hcy of 657 patients was (15.8 ± 7.80) μmol/L, of which 510(77.62%) were in line with the diagnosis of H-type hypertension. The level of Hcy in males was significantly higher than that in females, and the difference was statistically significant (P < 0.000 1). Compared with the different genotypes of the C677T locus, the TT type was higher than the CT type and CC type, and the difference was statistically significant (P < 0.05). There was no significant difference in Hcy levels between different genotypes at the A1298C locus (P > 0.05). CONCLUSION: The distribution of MTHFR gene polymorphism in the Han nationality hypertensive population in southern Anhui is significantly different from other regions, and it is also significantly related to the level of Hcy, which has obvious regional characteristics. The genetic detection technology combined with the determination of Hcy concentration can provide a scientific basis for the prevention and treatment of H-type hypertension in southern Anhui Province.