Air-hardening　bainitic　cast　steel　free　from　molybdenum　and　nickel　was　successfully　developed　whose　main　alloy　elements　were　silicon,　manganese,　chromium　and　boron.　Moreover,　there　were　a　few　titanium,　nitrogen,　calcium　and　rare　earth　elements　in　the　cast　steel　that　could　refine　and　purify　the　structure　of　steel.　The　effect　of　temper　temperature　on　the　structure　and　property　of　cast　steel　was　also　studied.　The　results　show　that　the　microstructure　of　the　cast　steel　quenched　at　920°C　and　cooled　by　air　is　fine　bainite.　The　toughness　of　cast　steel　increases　when　the　temper　temperature　increase.　The　temper　brittleness　appears　and　the　toughness　decreases　while　tempering　at　450°C.　Since　then,　the　toughness　increases　continuously　while　increasing　the　temper　temperature.　The　hardness　decreases　along　with　the　increase　of　temper　temperature.　The　decrease　of　hardness　is　slow　and　it　exceeds　HRC55　when　the　temperature　is　lower　than　300°C.　The　wear　resistance　decreases　along　with　the　increase　of　temper　temperature　under　the　condition　of　two-body　pin-on-disc　wear.　In　the　condition　of　impact　wear,　cast　steel　tempering　at　300°C　has　excellent　wear　resistance.　The　liner,　hammer　and　bucket　tooth　made　of　air-hardening　bainitic　cast　steel　free　from　molybdenum　and　nickel　have　good　service　effect,　whose　life-span　is　higher　than　that　of　high　manganese　steel　by　100%~300%.