Abstract:Xilushang iron smelting site with slag heap of large scale was confirmed in Yuan Dynasty (AD 1271-1368) by field and literature surveys. The slag belongs to byproduct of furnace operation according to its form and size. Many big agglutinates are mixed with slag, ores, limestone and coal nuggets in the form of coke. The slag containing low potassium and high sulfur indicates coal as the original fuel. Coal is probably roasted first to produce coke and then used for iron smelting.