The effects of superfine grinding on physicochemical properties and hypoglycemic activities in vitro of dietary fiber of balsam pear (DFBP) processed by extrusion were studied. Soluble dietary fiber content，water holding capacity and swell ability of superfine grinded dietary fiber of balsam pear (SGDFBP) in different time were analyzed. Glucose diffusion，α-amylase and α-glucosidase activity were also analyzed to assess the hypoglycemic activities of SGDFBP. The results showed that the soluble dietary fiber content，water holding capacity and swelling capacity of SGDFBP were 17.04%，16.29 mL/g，and 17.20% respectively, when the d50 of SGDFBP was 20 μm. X-ray diffraction pattern showed that the ratio of non crystalline area of SGDFBP increased during superfine grinding. Inhibition of glucose diffusion and reduction in enzymatic effect of α-amylase and α-glucosidase induced by DFBP were intensified by superfine grinding. Different ingredients of SGDFBP had different functions in hypoglycemic activity, especially pectin had better one. Superfine grinding processing could effectively improve the physicochemical properties and hypoglycemic activity in vitro of DFBP.