Abstract: The effects of K,Na or Zn on physical and chemical properties of six kinds of furnace hearth bottom refractories were investigated, and energy spectrum analysis were performed with scanning electron microscope on the ultra-micro-pore carbon brick and ceramic hearth brick after Na or Zn corrosion. The results are as follows:after the corrosion of K, Na or Zn, the bulk density of six kinds of refractories changes little, linear shrinkage increases slightly, the apparent porosity decreases, and the decreasing extent is positively correlated with the original apparent porosity. The compression strength of ceramic bottom brick and graphite carbon are greatly reduced, especially ceramic bottom brick.The thermal conductivity of ceramic bottom brick and ceramic hearth brick are greatly increased, while that of micro-pore carbon brick and ultra-micro-pore carbon brick are greatly reduced. For semi-graphite carbon bricks and graphite carbon bricks, the thermal conductivity varies with different erosion elements.