The　effects　of　lead,　arsenic　and　tin　in　pig　iron　on　structure　and　properties　of　iron　casting　were　studied　and　the　effectiveness　of　inoculation　of　ferro-silico-rare　earth,　ferro-silico-alkaline　earth　and　their　mixed　alloy　on　iron　casting　containing　tramp　elements　was　tested.　The　results　show　that　the　tramp　elements　such　as　Pb,　As　and　Sn　lead　to　the　formation　of　the　undercooled　graphite　and　carbide　network　and　the　deterioration　of　mechanical　properties　and　metallurgical　quality　index　of　iron　casting.　It　was　proposed　that　the　impurity　content　should　be　limited　to:　Pb　≤0.0055%,　As　≤0.013%　and　Sn　≤0.1%.　The　inoculation　of　ferro-silico-rare　earth,　ferro-silico-alkaline　earth　and　their　mixed　alloy　can　eliminate　the　harmfulness　of　the　tramp　elements　and　improve　the　quality　of　iron　casting.