After ADC drugs enter the blood circulation, they bind to the target antigen receptors on the surface of tumor cells. The newly formed ADC-antigen complex is internalized and degraded by lysosomes, releasing the payload and inducing tumor cell death. The payload is an important component of ADCs, and its activity and physicochemical properties directly affect the anti-tumor efficacy of ADCs drugs. The ideal payload should have sufficiently high cytotoxicity, low immunogenicity, high stability, modifiable functional groups, bystander killing effect, appropriate water solubility, and the target should be intracellular. Common payloads include tubulin inhibitors and DNA damaging agents.