Scrap resources are vital to the steel industry's sustainable development.The scrap index is defined as a criterion charactering the availability of scrap to the steel industry in the USA,Japan and China.The statistical data of the gross production of crude steel,scrap comsuption,imports and exports of scrap are all cited from 1958 to 2004.How the scrap resources of the USA,Japan and China changed cyclically in recent years are analyzed in relation to the demand for scrap in steel industry and relevant indices.Some suggestions are given to China's steel industry,including importing scrap,formulating reasonable standards of scrap and constructing national bases for scrap reserves.