||Nanoparticles with bone targeting ability and pH-sensitive were prepared with polyaspartamide (PASPAM) derivatives based on polysuccinimide (PSI) grafted with octadecylamine (C18), hydrazine (HYD) and polyethylene glycol (PEG). For the bone targeting, alendronate (ALN) which has bone affinity was grafted to PEG and doxorubicin (DOX) was conjugated with linkers of hydrazone bond which can be cleaved most effectively in an acidic environment. Under pH 5.0, ~75 % of dox was released from the nanoparticles due to the effective cleavage of HYD at the acidic condition. Also, ALN-PEG/C18/HYD-DOX-g-PASPAM particles were more effectively adsorbed on the surface of bone than PEG/C18/HYD-DOX-g-PASPAM. From in vivo antitumor activity test, the volume of tumor treated with ALN-PEG/C18/HYD-DOX-g-PASPAM was decreased (1550 nm3) when compared with PBS control sample (3850 nm3), proving ALN-PEG/C18/HYD-DOX-g-PASPAM as effective drug delivery system for the treatment of bone metastasis of breast cancer.