Poly-N-(vinylbenzyl)ethylenediamine is a functional polymer of scientific and economic significance．Owing to the disubstitution of ethylenediamine(EDA)during the direct amination of crosslinked chloromethylated polystyrene with EDA，predo-minant secondary crosslinlrlng usually oceurs，resulting with a low content of the ex-pected primary amino group．The disubstitution has been diminished to 13．3％by some improvements done in this laboratory，and SO the content of the primary amine has been raised to as high as 43.3％．In another method．to avoid the EDA disubstitution one of the two primary amino groups in EDA was acetylated prior to the amination procedure，and the primary amino group was regenerated through a hydrolysis procedure．The two investigated methods resulted mainly in the desired monosubstituted products．The products obtained from these two different methods were applied to the separa-tion and purification of streptomycin，of sh owed the desirable properties．