Aim To study the relationship between plasma folic acid level and essential hypertension (EH) in Kazak of Shawan County, Xinjiang. Methods 641 Kazaks and 702 Han nationalities in Shawan County of Xinjiang were selected as research subjects, of which 654 were in EH group and 689 were in control group with normal blood pressure. General data of sex, age, body mass index, waist-hip ratio and biochemical indexes were collected. Blood samples were collected and plasma folic acid levels were measured by ACCESS automatic particle chemiluminescence immunoassay system. Results (1)The plasma folic acid level of Kazak was lower than that of Han nationality (P＜0.01); The plasma folic acid level in EH group was lower than that in control group (P＜0.01); The plasma folic acid level in males was lower than that in females (P＜0.01). (2)After sex stratification, the plasma folic acid level in male Kazak EH group was significantly lower than that in control group (P＜0.05), and the plasma folic acid level in female Han nationality EH group was significantly lower than that in control group (P＜0.01). In Kazak population, plasma folic acid level in males was significantly lower than that in females (P＜0.05). The plasma folic acid level of Kazak was significantly lower than that of Han nationality in both male and female (P＜0.01). (3)The plasma folic acid level of EH group and control group was significantly lower in Kazak than that in Han nationality (P＜0.01). In EH group and control group, the plasma folic acid level of Kazak was significantly lower than that of Han nationality, both male and female (P＜0.05). Conclusions The plasma folic acid level of Kazak in Shawan County of Xinjiang is lower than that of Han nationality, and that of EH patients is lower than that of normal people. There is a significant correlation between plasma low folic acid level and high prevalence of EH in Kazak.