Amphiphilic block copolymer and preparation method thereof and micellar drug-loading system formed by same with antitumor drug

The present invention relates to an new type amphiphilic block copolymer and preparation method thereof, and a micellar drug-loading system formed by the copolymer with an antitumor drug. The amphiphilic block copolymer comprises an amphiphilic chain segment and a hydrophobic chain segment, wherein the end-group of the hydrophobic chain segment is blocked with a hydrophobic group. The amphiphilic block copolymer of the present invention employs a polyethylene glycol monoethylether (or polyethylene glycol)-polyester block copolymer with a recognized safety as a base material and the end-hydroxy of the polyester chain segment is modified with a hydrophobic group, which not only improves the compatibility of the drug molecule with the hydrophobic chain segment of the block copolymer and increases the force therebetween, but also provides a bigger space for accommodating the drug molecule; the prepared micelle can more effectively confine the drug molecule in the core of the micelle so that the drug molecule does not dissolve easily, thus the drug-loading micelle with high stability is obtained.