Different poly(N-isopropylacrylamide-co-hydroxyethyl methacrylate) copolymers (P(NIPAM-co-HEMA)) were synthesized from N-isopropylacrylamide (NIPA) and hydroxyethyl methacrylate (HEMA) comonomers by both radical and radiation polymerizations for comparison. PLLA-g-P(NIPAM-co-HEMA) graft copolymers were synthesized from L-lactide and respective P(NIPAM-co-HEMA) copolymers by ring opening polymerization. Both NMR and FTIR analyses demonstrated the PLLA chains have been grafted on to the P(NIPAM-co-HEMA) backbone. These graft copolymers revealed the cloud point temperature higher than that of PNIPAM homopolymer as determined by optical transmittance. The graft copolymers self-assembled into micelles with regularly spherical structures as observed by atomic force microscopy (AFM). The properties of these graft copolymers are interesting for the drug delivery system.