Abstract: Twelve kinds of Carya illinoensis in Luquan, Yunnan Province have been collected for measuring the morphology and determining the contents of the crude fiber. The response surface methodology was used to optimize the determination of crude fiber content. The results show that they are rich in crude fiber, while significant differences have been found in morphologies of C.illinoensis. The length ranges from 2.50 to 4.80 cm, the width ranges from 1.60 to 2.10 cm and the weight ranges from 4.00 to 9.50 g. The optimal extraction conditions for crude fiber are extraction time 45 min, lye concentration 10%, fineness of 50 mesh sieve detecte the highest content of crude fiber, and crude fiber content of 5%-8%.