Objective To observe the effect of curcumin on hepatic 11β-hydroxysteroid dehydrogenase type 1 (11β-HSD1) expression and insulin resistance in rats with nonalcoholic fatty liver disease (NAFLD). Methods Thirty- two male Wistar rats were randomly divided into four groups: control, NAFLD model, low-dosage curcumin treatment (C1) and high-dosage curcumin treatment (C2) groups. The NAFLD model was established by a high-fat / high-sugar diet. After 8 weeks of the diet, the C1 and C2 groups were given 200 and 400 mg / ( kg·d) curcumin, respectively, by intragastric administration for 8 weeks. Results Compared with the model group, the NAFLD was significantly improved in the C1 and C2 groups, expressed as the reduction of the fatty liver index, serum lipids, liver lipid deposition, improvement of liver function and pathological changes. Insulin resistance was also significantly improved. The relative expression levels of 11β- HSD1 mRNA and protein in liver tissue were significantly lower in the C1 ( 0. 157 ± 0. 013 and 0. 264 ± 0. 062, respectively) and C2 groups (0. 091 ± 0. 009 and 0. 191 ± 0. 021, respectively) than those in the model group (0. 264 ± 0. 015 and 0. 477 ± 0. 074, respectively) (P< 0.05, P< 0.01). All curcumin treatment effects were dose-dependent. Conclusions Curcumin significantly improved NAFLD in rats, and this effect may be related to the inhibition of 11β- HSD1 expression and the improvement of insulin resistance.