A PEG-oligopeptide-irinotecan conjugate with a general formula (I) and the pharmaceutical composition comprising the conjugate are disclosed. In the conjugate, PEG represents polyethylene glycol with a molecular weight of 300-60,000 Daltons (AA)i represents an oligopeptide, AA represents the same or different amino acids in the oligopeptide i is an integer of 2-12 representing the number of amino acids in oligopeptide j is an integer of 2-12 representing the number of irinotecan connected with the oligopeptide. In the conjugate, each terminal group of PEG can link with multiple irinotecans through oligopeptides, thereby greatly increasing the drug-loading capacity. Modification of the hydrophilic polymer can provide protection for the irinotecan, thereby improving drug absorption, prolonging the action time, enhancing the efficacy, reducing the dose and avoiding the toxic and side-effects.
