The present invention relates to a conjugate of hydrophilic polymer-multicarboxyl oligopeptide and drug molecule of the following formula: ##STR00001## wherein: P is a hydrophilic polymer; m is an integer of 2.about.12; j is an integer of 1.about.6; R.sub.i is a group selected from H, C.sub.1-12 alkyl, substituted aryl, aralkyl, heteroalkyl and substituted alkyl; X and Z are linking groups; and TA is drug molecule. The conjugate has low toxicity and an ability to carry more than one drug molecule to improve solubility, sustain and control drug release, and has a remarkably enhancing effect especially to antitumor drug such as paclitaxel and camptothecin etc.