β-nucleated　controlled-rheology　polypropylene　random　copolymers　(CRPPRs)　were　prepared　by　peroxide-initiated　degradation　via　adding　dicumyl　peroxide　(DCP)　to　β-nucleated　PPR.　Melt　flow　index　(MFI)　and　mechanical　properties　of　β-nucleated　PPR　and　CRPPRs　were　analyzed　and　compared　with　PPR.　Wide-angle　X-ray　diffractometer　(WAXD),　differential　scanning　calorimeter　(DSC)　and　polarized　light　microscope　(PLM)　were　used　to　study　the　crystalline　structure　and　morphology.　The　results　indicate　that　the　MFI　of　β-nucleated　CRPPR　increases　linearly　with　increasing　DCP　content.　The　strain　hardening　rate　and　impact　strength　of　β-nucleated　CRPPRs　well　reflect　the　degree　of　degradation　and　β-phase　content.　No　significant　change　of　yield　strength　and　strain　at　break　is　seen　with　increasing　DCP　content,　except　for　an　increase　of　the　latter　when　DCP　content　reaches　0.15　wt%.　The　maximum　crystallinity　is　observed　at　0.05　wt%　DCP.　β-nucleated　CRPPRs　show　increased　crystallization　temperature　and　decreased　β-crystal　content　and　crystal　size　as　DCP　content　increases.　©　2011　Elsevier　Ltd.　All　rights　reserved.