The star-shaped block copolymers were prepared by ring-opening polymerization of ε-caprolactone in the presence of multiarm PEG using stannous octoate as a catalyst．Based on these star-shaped PEG-b-PCL

soluble macromers terminated with acrylate groups were synthesized．The amphiphilic nature of the macromers causes them to assume a micellar conformation in water

which enables them to undergo rapid polymerization using photoinitiator under UV radiation．Macromers and their hydrogels were characterized by 1H-NMR、FTIR、DSC、TGA、ESEM、gel content and swelling ratio etc．It is shown that dried gels absorb water rapidly

and hydrogels have high swelling ratio and water content．With the increase of arm numbers of PEG

the temperature of the melting peak of dried gels and the swelling ratio of hydrogels decrease；The photograph of ESEM indicated clearly the network structure of the hydrogel．