A series of random and block poly (L-lactide-co-ε-caprolactone) (PCLA) copolymers with different composition are prepared using starmous octaoate as catalyst. The effects of the amount of initiator on the intrinsic viscosity have been investigated. The structure of the PCLA copolymers is characterized by means of nuclear magnetic resonance (NMR), Fourier transform infrared spectrum (FTIR), differential scanning calorimetry(DSC) and X- ray diffraction (XRD) methods. It is shown that the synthesis condition and the composition of copolymers have obvious influence on the structure of PCLA copolymers. Hydrolytic degradation of the copolymers in a PBS solution of pH 7.4 at 37.0 ℃ shows that the copolymers of different compositions degrade at different rates .