Poly(L-lactide)/poly(e-caprolactone) diblock, triblock and four-armed copolymers with the same monomer feed ratio (50/50) were synthesized by ring opening polymerization of successively added e-caprolactone and L-lactide, using isopropanol, ethylene glycol, or pentaerythritol as initiator and nontoxic zinc lactate as catalyst. The resulting copolymers were characterized by 1HNMR, SEC, FT-IR and XRD, which confirmed the blocky characteristic of the copolymers. Various solution cast films were allowed to degrade at 37 oC in the presence of proteinase K, and the degradation was monitored by DSC, SEC, 1HNMR and ESEM (Environmental Scanning Electronic Microscopy). The effects of chain structure, block length and phase dispersion on degradation were discussed. No obvious thermal property changes and compositional changes were detected during degradation. ESEM was used to follow the morphology evolution of solution cast films prepared from these block copolymers.