This study was conducted to develop a drug delivery carrier with specific drug release profile to-wards tumor cells based on the fact that tumor cells have lower pH and higher concentration of a reducing agent than normal cells. Hydrazone bond was used as a pH sensitive linker that is stable at pH 7.4 but unsta-ble at pH 5.0. Doxorubicin (DOX) was conjugated on poly(aspartyl hydrazide) (PAHy) backbone with hydra-zone bond. N-succinimidyl 3-(2-pyridyldithio) propionate (SPDP) crosslinker grafted on the backbone formed a disulfide bond in a normal cell, but the disulfide bond was dissociated in a tumor cell. In a normal cell drugs were released with only disregarded amount, but in a tumor cell, drugs were rapidly released as a consequence of breaking of hydrazone bonds and disulfide bonds. Characterization of the dual sensitive particle was fully investigated. The specific drug release profile under tumor condition and anticancer therapeutic effect was also evaluated.