Poly(propylene carbonate)/starch (PPC/starch) composites with different starch contents were prepared by melt compounding. The biodegradability of the composites was studied by soil burial for a period of 6 months. FTIR study, thermal analysis and morphology observation indicated clearly the changes of the buried specimens. The weight loss curves and the molecular weight changes of the specimens revealed a three-stage biodegradation, corresponding to the propagation of microorganisms, the degradation of starch and the degradation of PPC. The experimental results showed that the addition of starch accelerated the degradation of PPC. Specimens with higher starch content exhibited greater weight loss in the second stage and smaller weight loss in the third stage.