The　effect　of　Cr　content　on　the　microstructure　and　mechanical　properties　of　carbidic　austempered　ductile　iron　(CADI)　was　studied　by　means　of　optical　microscopy　(OM),　X-ray　diffractometry　(XRD),　scanning　electron　microscopy　(SEM),　Rockwell　hardness　testing,　pendulum　impact　testing　machine　and　ring-on-block　wear　tester.　The　results　show　that　with　the　increase　of　Cr　content　the　volume　fraction　of　graphite　and　nodularity　rate　of　as-cast　ductile　iron　decrease　gradually,　but　carbide　content　increases,　and　the　diameter　of　graphite　reaches　the　maximum　followed　by　decrease.　Then,　the　specimens　were　austenitized　at　900　degrees　C　for　100　min　and　austempered　at　300　degrees　C　for　100　min.　The　hardness　and　wear　resistance　of　CADI　reach　maximum　when　Cr　content　is　1.42　wt.-%　and　then　decrease　with　the　increase　of　Cr　content,　and　the　impact　toughness　decreases　gradually.　Taking　the　impact　toughness　into　consideration,　the　comprehensive　mechanical　property　is　best　when　Cr　content　is　0.96　wt.-%.