As a representative of the development direction of the new generation of antibody technology, antibody drug conjugates (ADCs) have high specificity of antibodies and high toxicity of cytotoxic drugs to tumors. Cytotoxic Agents play an anti-tumor role in ADCs, which can affect the expected efficacy of target tumors. Its chemical structure, coupling mode and coupling number also affect the biological activity of the antibody. In theory, cytotoxic substances such as chemotherapeutic drugs, toxins and radionuclides that have great killing effects on tumor cells can be used as cytotoxic molecules of ADCs.