Objective To study the effects of pioglitazone (PGZ) on the expressions of 11β-hydroxysteroid dehydrogenase type 1(11β-HSD1) in central nervous system of diabetic rats and its asociation with cognitive function. Methods Thirty male SD rats were equally randomized into Control group (C group)， Diabetic group (D group) and Diabetes+Pioglitazone group (DP group). Morris-water maze was used to test the cognitive function after 8 weeks. Western Blot was used to detect the expressions of 11β-HSD1 in hippocampus and hypothalamus. Results In Morris water maze， the number of crossing the platform in D group were significantly less than C group and DP group (P＜ 0.01). The 11β-HSD1 expressions in hippocampus and hypothalamus of D group were significantly increased than C group and DP group， while the 11β-HSD1 expressions of DP group were significantly increased than C group (P＜ 0.01). Conclusion Pioglitazone may improve cognitive function in diabetic rats， partly through the decrease of 11β-HSD1 expressions in hippocampus and hypothalamus.