SGCI(Spheroidal Graphite Cast Iron), CVGCI(CV Graphite Cast Iron) and FGCI(Flake Graphite Cast Iron) having different contents of Mn(0.25%∼0.85%) and Ni(0.3%∼1.2%) were produced, respectively. The thermal expansion and thermal conductivity of the cast iron were investigated in the temperature range of 50℃∼300℃. As the graphite nodularity of the cast iron increases, thermal expansion coefficient increases, thermal conductivity and electrical conductivity to thermal conductivity ratio decrease. The thermal expansion coefficient of the cast iron increases with increasing Mn content and decreases with increasing Ni content. The thermal conductivity of the cast iron decreases with increasing Mn and Ni contents.