Biodegradable poly(L-lactide) (PLLA)/polyhedral oligomeric silsesquioxanes (POSS) nano-composites were prepared in this work via solution and coagulation method at various POSS loading in order to get a better dispersion of POSS in the PLLA matrix. Scanning electron microscopy observation indicates that POSS were nicely dispersed in the PLLA matrix. The overall crystallization rates are faster in the PLLA/POSS nanocomposites than in neat PLLA and increase with increasing the POSS loading; however, the crystallization mechanism and crystal structure of PLLA remain unchanged despite the presence of POSS. The storage modulus has been apparently improved in the PLLA/POSS nanocomposites with respect to neat PLLA, while the glass transition temperatures vary slightly between neat PLLA and the PLLA/POSS nanocomposites. It is interesting to find that the hydrolytic degradation rates have been enhanced obviously in the PLLA/POSS nanocomposites than in neat PLLA, which may be of great use and importance for the wider practical application of PLLA. The erosion mechanism of neat PLLA and the PLLA/POSS nanocomposites was further discussed.