The disclosure discloses a linker compound, a polyethylene glycol-linker conjugate and a derivative thereof, and a polyethylene glycol-linker-drug conjugate. The linker compound as well as the conjugate thereof with the polyethylene glycol and the derivative thereof may be used for modifying a drug, and a modification reaction is simple and easy to carry out. Moreover, a reaction yield is high, and an application range of the modified drug is wide. The modified drugs gradually degrade from a chain of the conjugate in vivo, and may stay in a lesion (such as a cancer site) for a longer period of time, achieving purposes of sustained and controlled release, reducing an administration frequency, and greatly improving a bioavailability of the drug and a patient compliance.
