Photoreactive crosslinkers are a class of compounds that can initiate chemical crosslinking reactions by light irradiation. Aryl azides (AZs), benzophenones (BPs), diaziridines (DAs) and 2-aryl-5-carboxytetrazoles (ACTs). Under ultraviolet excitation of a specific wavelength, the corresponding intermediates are nitrene, diradical, carbene and carboxynitrile imine. Among them, carbene-mediated photoaffinity labeling is widely used in drug target recognition.