Abstract: Dietary fiber was extracted from bamboo powder. Laser granulometer and SEM were used to study the effect of superfine grinding on the microstructure of bamboo powder under different grinding time.The effects of superfine pulverizing on the functional properties of dietary fiber in bamboo powder were researched. The results showed that the main ingredient in dietary fiber by superfine pulverizing was IDF ( more than 75%) , the smaller particle size of dietary fiber powder, the higher SDF content and the lower IDF content were.When superfine pulverizing time reached 4 h, the D⁵⁰ was 32.44 μm, particle size distribution was concentrated in 20⁵0 μm, after ultrafine comminution time increasing, the particles started to reunite.The D⁵⁰ of the pulverized powder at 5 h and 6 h reached 45.22 μm and 44.60 μm, respectively.With superfine pulverizing technology, dietary fiber functional properties improved to varying degrees, the capacity of adsorbing NO₂^- and sodium cholate, the property about expansibility, water-holding capacity, oil-holding capacity were higher than original superfine.It concluded that a certain degree of superfine pulverizing of dietary fiber can improve its functional properties.