A　novel　highly　active　β-nucleating　agent,　β-cyclodextrin　complex　with　lanthanum　(β-CD-MAH-La),　was　introduced　to　isotactic　polypropylene　(iPP).　Its　influence　on　isothermal　crystallization　and　melting　behavior　of　iPP　was　investigated　by　differential　scanning　calorimeter　(DSC),　wide-angle　X-ray　diffraction　(WAXD),　and　polarized　light　microscopy　(PLM).　WAXD　results　demonstrated　that　β-CD-MAH-La　was　an　effective　β-nucleating　agent,　with　β-crystal　content　of　iPP　being　strongly　influenced　by　the　content　of　β-CD-MAH-La　and　the　isothermal　crystallization　temperature.　The　isothermal　crystallization　kinetics　of　pure　iPP　and　iPP/β-CD-MAH-La　was　described　appropriately　by　Avrami　equation,　and　results　revealed　that　β-CD-MAH-La　promoted　heterogeneous　nucleation　and　accelerated　the　crystallization　of　iPP.　In　addition,　the　equilibrium　melting　temperature　(T　m0)　of　samples　was　determined　using　linear　and　nonlinear　Hoffman-Weeks　procedure.　Finally,　the　Lauritzen-Hoffman　secondary　nucleation　theory　was　applied　to　calculate　the　nucleation　parameter　(Kg)　and　the　fold　surface　energy　(σe),　the　value　of　which　verify　that　the　addition　of　β-CD-MAH-La　reduced　the　creation　of　new　surface　for　β-crystal　and　then　led　to　faster　crystallization　rate.　©　2011　Wiley　Periodicals,　Inc.