The synthesis of macromolecular-drug and its behavior during the process of hydrolysis at the temperature near that of human body were studied. β-acryloxypropionic acid-styrene copolymer was used as drug carrier and it reacted with the isoniazidum drug through ma-cromolecular reaction. The IR analysis of products demonstrated that the conversion of car-oxylic group could reach 61%. The results of neutral or acidic hydrolysis of P(St-co-APA) attaching isoniazidum showed that the hydrolysis of the macromolecular-drug could be con-trolled due to the particular structure of acryloxypropionic acid unit.