The object of this study was to find an optimum work standard for economic manufacturing of nodular graphite iron in Korea. A 0.5 ton/hr capacity acid lined existing cupola was chosen for melting because the majority of 290 foundries in Korea operate acid lined anthracite fired cupola. Nodular graphite iron costed from the melts resulted from various (imported) coke ratio and air blow rate were examined their microstructure, composition and mechanical properties. The optimum was found to be 14 w/o coke ratio, 24㎥/min blow rate and 0.04% residual magnesium; this was rather cheaper way than a case that uses anthracite fuel in this country.