Abstract: Objective To study the expression of HIF-1αin the peripheral blood and the ratio of Treg and Th17 cells in T cells in patients with nonalcoholic fatty liver disease(NAFLD),and to explore the relationship between those and pathology of NAFLD. Methods A total of 39 patients who were diagnosed as nonalcoholic fatty liver disease in our hospital from October,2015 to April,2016 and 20 healthy volunteers were collected in this study.Flow cytometry were used to measure and analyze the portion of CD4⁺/CD25⁺/Foxp3⁺ Treg cells and CD4⁺/IL17⁺ Th17 cells in total CD4⁺T lymphocytes.Enzyme linked immunosorbent assay(ELISA) were employed to test the expression level of HIF-1α.Expression of HIF-1α and the portion of Treg cells and Th17 cells were compared between two groups.They were also compared between NAFLD patients in the fat group (BMI ≥ 28 kg/m²) and those in the non-fat group(BMI<28 kg/m²).Student's t test and chi-square test were employed in the statistics. Results NAFLD patients had a much higher expression level of HIF-1α (t=11.284,P<0.001).The portion of Treg and Th17 cells in total CD4⁺T lymphocytes were significantly higher in NAFLD group than in control group (t=11.313,P<0.001 and t=8.737,P<0.001) and the ratio of Th17/Treg was also higher (t=4.055,P<0.001).Non-fat NAFLD patients expressed obviously higher level of HIF-1α than fat NAFLD patients(t=2.035,P<0.05).The portion of Treg and Th17 also increased in non-fat NAFLD patients (t=2.066,P<0.05 and t=2.089,P<0.05) but no significant difference of the ratio of Th17/Treg was observed (t=0.048,P>0.05). Conclusion Patients with NAFLD has higher expression level of HIF-1α and imbalance of Th17/Treg.HIF-1α and balance of Th17/Treg could be involved in the onset and development of NAFLD,and may have relationship with insulin resistance to some extent.