The poly(epsilon-caprolactone) (PCL)/alpha-cyclodextrin (alpha-CD) inclusion complex (PCLIC) was successfully, prepared, and its effect on the thermal behavior and mechanical properties of PCL was thoroughly studied. It is shown that the addition of PCLIC greatly increased the crystallization rate and thermal stability of the PCL. The Young's modulus and yield strength of PCL/PCLIC composite are about 2 and 1.3 times of the pure PCL, and the elongation at break of the PCL/PCLIC composites kept above 350%,, when the PCLIC composition is 15 wt %. It is shown that PCLIC is a good enforcing biofiller for the PCL (C) 2009 Wiley Periodicals, Inc. J Appl Polym Sci 112: 23512357, 2009