According to the invention, four-arm PEG (polyethylene glycol), six-arm PEG and multi-arm PEG are respectively connected with oritavancin by utilizing the characteristics that the multi-arm PEG is non-toxic and easy to combine. A multi-arm PEG loaded oritavancin prodrug not only has good water solubility, but also is most importantly characterized in that one multi-arm PEG chain can be connected with a plurality of oritavancin residues, so that the loading rate of the drug is greatly increased, the half-life period of the drug is greatly prolonged, the existence time of the drug in plasma is remarkably prolonged, and the curative effect is improved.