Abstract: Pulping properties has been studied on age 3 and age 6 A. crassicarpa. The research shows that the mean fiber length of juvenile A. crassicarpa is about 0. 9 mm, the content of holocellulose is a- bout 78% , the content of Klason lignin is about 22%~23%;the yield of Kraft pulp of juvenile A. cras- sicarpa is about 48%~50% , the pulp tensile length of juvenile A. crassicarpa can reach to 7 000 m, and tearing index can be more than 10 mN ?m2/g. Age 3 and age 6 A. crassicarpa kraft pulp with nearly the same kappa number were made under their respective optimum cooking conditions. A com- prehensive evaluation has been discussed by comparing their properties of pulping, beating, strength and bleaching.