Crosslinkers are mainly used to connect antibodies and toxins. The linker that connects cytotoxic drugs to monoclonal antibodies is the core part of ADC. One of the biggest challenges in developing effective ADCs is to choose a suitable crosslinker. The crosslinker must be able to release the cytotoxic drug in an active form in or near the target cell. The crosslinker is the basis for the effective delivery of cytotoxic drugs by ADC and is also a key factor in determining the toxicity of ADC products. Premature release of drugs in the circulation can lead to systemic toxicity and a lower therapeutic index. The choice of linker usually depends on the target, the drug, the internalization and degradation of the antibody-antigen complex, and the properties of the drug used.