Antibody drug conjugate has emerged as one of the most successful drug delivery systems in recent years. Leveraging the inherent self-assembly and efficient intracellular internalization capabilities of DNA nanostructures, this study aimed to develop antibody-DNA nanostructure conjugates based on gemcitabine, which drug antibody ratio can reach 17.8. The conjugate enhances cytotoxicity by assembling gemcitabine into DNA nanostructures to deliver it as polymers, and exhibiting the same pharmacological mechanism as gemcitabine, inducing apoptosis and necroptosis of tumor cells. The evaluation results of flow cytometry showed that the efficacy of the conjugate was more than 20 times that of gemcitabine. Similar to traditional ADC, the antibody on the conjugate confers targeting ability to gemcitabine. And the conjugate shows potent anti-tumor effects both in vivo and in vitro, while lacking the hematotoxicity and bone marrow suppression associated with gemcitabine. In summary, this study provides a novel antibody drug conjugate, which expands the repertoire of available cytotoxic agents and effectively addresses the challenges encountered in the development and application of gemcitabine.