Poly(L-lactic acid)-block-poly(poly(ethylene glycol) monomethacrylate) (PLLA-b-PPEGMA) has been prepared by the ring-opening polymerization of lactide with a double-headed initiator, 2-hydroxyethyl 2'-methyl-2'bromopropionate (HMBP), followed by atom transfer radical polymerization (ATRP) of poly(ethylene glycol) monomethacrylate (PEGMA) PLLA-b-PPEGMA nanoparticles with encapsulated Fe3O4 are prepared by a solvent evaporation/extraction technique, and then further functionalized with folic acid, a cancer targeting ligand. Our results show that such functionalized PLLA-b-PPEGMA nanoparticles have good potential as carriers for targeted drug delivery in cancer treatment.