A series of block copolymers from D,L-lactide and poly(ethylene glycol) (PEG) with different molecular weights were synthesized by using Al(i-Bu)(3)-H3PO4-H2O as the initiator and identified by H-1-NMR, GPC, and DSC. The elongation at break of the material increased when PEG was introduced, but the strength of the material decreased. The copolymers degrade more smoothly in vitro than did the PLA homopolymer.