The invention relates to methoxy polyethylene glycol-poly-N-isopropyl acrylamide-metal tetramino phthalocyanine and a preparation method therefor and belongs to the field of photodynamic therapy. Methoxy polyethylene glycol-poly-N-isopropyl acrylamide-metal tetramino phthalocyanine is used for solving the problem that the existing phthalocyanine photosensitizer is poor in water solubility and low in tumor targeting performance and the application in the photodynamic therapy is limited by unstable PI-PI accumulative action. Methoxy polyethylene glycol-poly-N-isopropyl acrylamide-metal tetramino phthalocyanine disclosed by the invention has the skeleton symbol of MPEG-PNIPAM-MTAPc, wherein MPEG means methoxy polyethylene glycol, PNIPAM means poly-N-isopropyl acrylamide, and MTAPc means metal tetramino phthalocyanine. The preparation method disclosed by the invention comprises the steps: firstly, preparing an ATRP (Atom Transfer Radical Polymerization) initiator MPEG-X from MPEG-OH and a halogenated substance; secondly, initiating an NIPAM (N-isopropyl acrylamide) monomer to subject to ATRP by the initiator, so as to obtain a temperature-sensitive diblock copolymer MPEG-PNIPAM-X; then, carrying out terminal group functionalization on the MPEG-PNIPAM-X with MA (Maleic Anhydride), so as to obtain MPEG-PNIPAM-MA-X; and finally, bonding MTAPc to the MPEG-PNIPAM-MA-X, thereby obtaining the MPEG-PNIPAM-MTAPc. The prepared photosensitizer is good in water solubility and high in tumor targeting performance, is not liable to aggregation in aqueous solutions and is a phthalocyanine photosensitizer with development potential.