In this study, there are two parts of experiments. First part is about the pH/temperature sensitive tri-block copolymer poly(AAc-b-NIPAAm-b-AAc), which is synthesised by RAFT polymerization of acrylic acid and N-isopropylacrylamide .The second part of this research is about the sulfonamide-based pH-sensitive hydrogel, which is synthesized by redox copolymerization of sulfamethazine monomer(SAM) and N,N-Dimethylacrylamide (DMAAm) with the thermo-crosslinkable monomer N-methylol acrylamide(NMA) as crosslinking agent. The first part is the experiment of poly(AAc-b-NIPAAm-b-AAc) copolymer. The main discussion is about the influences of PAAc and PNIPAAm chain segments on tri-block copolymer’s chemical properties and physical properties(ex: temperature- sensitivity of copolymer (lower critical solution temperature LCST)、micelle forming conditions、granulometry、 micelle morphology 、thermal properties). The second part is divided into two sections. The synthesis of pH-sensitive random copolymer poly (SAM-DMAAm) was discussed in first section. By regulating the monomer feed ratio, the starting point of copolymer’s pH-sensitivity can be controlled in the range of pH6.8~pH7.4. Then, the sulfonamide-based pH-sensitive hydrogel was prepared by introducing thermo-crosslinkable monomer NMA to the copolymerization system and going through the thermo-curing process. By comparing the pH-sensitive behaviors of linear random copolymers and hydrogels, the influences of crosslinking effect on the pH-sentivity and on the swelling-shrinkage capacity of hydrogel was discussed in the final section.