Provided are a PEG-naloxone conjugate of general formula (II) and a pharmaceutical composition comprising the conjugate. In the conjugate, n is an integer in the range of 1 - 20. Also provided is a three-branched or four-branched conjugate of PEG and naloxone. Structural modification of naloxone with a hydrophilic polymer improves the pharmacokinetic properties of the drug, increase the water solubility of naloxone, improve the in vivo distribution of the drug, reduce the side effects of naloxone on central nervous system, and relieve bowel dysfunction and constipation caused by chronic administration of opioids. Also provided are a pharmaceutical composition comprising the conjugate of the invention and use of the conjugate.
