A series of well-defined graft copolymers, consisting of poly(tert-butyl acrylate) backbone and poly(methyl acrylate) side chains, were synthesized by the combination of reversible addition-fragmentation chain transfer (RAFT) polymerization and atom transfer radical polymerization (ATRP). A new acrylate monomer containing ATRP initiation group, tert-butyl 2-((2-bromopropanoyloxy)methyl)acrylate, was First prepared, which can be homopolymerized or copolymerized with tert-butyl acrylate by RA FT in it controlled way to obtain well-defined homopolymers and copolymers with narrow molecular Weight distributions (M-w/M-n < 1.18). The reactivity ratios were determined by Fineman-Ross and Kelen-Tudos methods, respectively. The density of ATRP initiating groups call be tuned by the feed ratio of the comonomers. These polymers directly initiated ATRP of methyl acrylate to Synthesize well-defined poly(tert-butyl acrylate)-g-poly(methyl acrylate) graft copolymers (M-w/M-n < 1.28) with controllable grafting densities via the grafting-from strategy without any polymeric functional group transformation. Finally, the poly(tert-butyl acrylate) backbone was selectively, hydrolyzed in acidic environment without affecting the poly(methyl acrylate) side chains to give poly(acrylic acid)-g-poly(methyl acrylate) amphiphilic graft copolymers.