Abstract: The dietary fiber was as material which was extracted from Pleurotus eryngii residue using enzyme hydrolysis method.The application of the high-quality dietary fiber in crisp biscuit was researched. Based on the formulation of ordinary crisp biscuit, the optimum content and particle sizes of dietary fiber from Pleurotus eryngii residue in crisp biscuit were analyzed using sensory evaluation, texture analysis, color value testing and flavor analysis.The results showed that the color, texture and taste were best in the dietary grain size of 120 mesh. Based on the mesh to evaluate the sensory score, it was firstly increased and then decreased with the adding of dietary fiber, especially the score of 10 percent of dietary fiber was higher than others.Totally, there were obvious difference in hardness and brittleness ( p < 0.05) , while no significant difference in chewiness and cohesion ( p > 0.05) .After adding dietary fiber, color value L*of biscuit decreased while a*and b*value increased.Meanwhile, it also had a positive effect on the flavor of the biscuits.Then the optimum adding amount of Pleurotus eryngii dietary fiber was10% with the particle size in 120 mesh, the quality of crisp biscuit was best.