A ligand-mediated nanoparticulate drug carrier composed of heparin-based copolymers was designed to achieve targeted drug delivery for chemotherapy. Novel amphiphilic copolymers composed of heparin with antitumor activities and poly(${eta}$-benzyl-L-aspartate) (PBLA) with the potential capacity for serving as pH-responsive drug release reservoirs were synthesized by conjugating PBLA as a hydrophobic segment to the hydrophilic heparin backbone. To introduce folate ligands for tumor targeting to the heparin/PBLA copolymers, folate-conjugated heparin/PBLA copolymers were prepared with various compositions by varying the feed molar ratio of PBLA, amine-terminated folate (or folate-conjugated PEG) to heparin. The synthesis and composition of the heparin-based copolymers were confirmed by $^1H$ NMR and colorimetric methods, respectively. Heparin-based amphiphilic copolymeric nanoparticles were prepared by micelle formation in an aqueous solution. The properties of the micelles were described by the critical micelle concentration (CMC), size and size distribution. The CMC values of heparin-based copolymers decreased with increasing concentration of the PBLA hydrophobic segments in the copolymers. The conjugation of folate (or folate-conjugated PEG) with hydrophilic nature into heparin/PBLA copolymers affected the free chain-micelle equilibrium, leading to an increase in the CMC values. The particle size of the heparin-based copolymers determined by light scattering measurements ranged from 100 to 130 nm, depending on the molecular weight and composition of the copolymers. Field emission scanning electron microscopy showed that the heparin-based copolymeric particles had a sub-micron size with spherical shape.