A serial of star-shaped poly(ε-caprolactone)-b-poly(ethylene oxide) (SPPCL-b-PEO) block copolymers with porphyrin core were successfully synthesized from ring-opening polymerization (ROP) of ε-caprolactone (CL) initiated with porphyrin core, followed by coupling reaction with a hydrophilic polymer poly(ethylene oxide) (PEO) shell. The structure of this novel copolymer were synthesized and thoroughly characterized by Nuclear Magnetic Resonance (NMR), Gel Permeation Chromatography (GPC), Fourier Transform Infrared Spectroscopy (FTIR). Notably, the as-prepared porphyrin-cored star-shaped copolymer could self-assembly into different structures determined by transmission electron microscopy (TEM) and dynamic lighting scattering (DLS), which provides the great potential of using this well-defined photodynamic therapy material for drug delivery system. Particularly, the doxorubicin-loaded SPPCL-b-PEO nanosphere exhibits property of pH-induced drug release. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40996.