AKD is an important internal size for paper pulp fiber. With recycled economy development, regenerated paper fiber becomes an important resource. In this paper, AKD is used as a modification aid by internal sizing method. It shows that the change of the dosage of AKD influences regenerated paper fiber Cobb value, but has no influence to paper surface strength. The proper pH value is from 7 to 9. The temperature has no influence to regenerated paper fiber Cobb value and paper surface strength. Appropriate modified starch is good for AKD modification fiber and increase of the surface strength of paper made from modified fiber by AKD. Amphoteric starch is better than cationic starch. Other added substances such as PEI, MPEI and PAE can improve the modification of paper fiber modified by AKD. So the adsorption of modified paper fiber decrease and the surface strength of paper modified fiber increase.