研究了原铁液中硫对薄壁球墨铸铁显微组织的影响，结果表明：含硫量很低的原铁液白口倾向大、石墨球数少；稀土最佳加入量随原铁液含硫量增加而增加；稀土的适宜控制范围随原铁液含硫量的减少而变窄。球铁中硫量的控制应有上限，也应有下限。 The effect of sulfur on the microstructure of the thin-walled nodular cast iron was investigated. The results show that the original white iron with a low sulfur content tends to have a large white splatter and a small number of graphite spheres. The optimum amount of rare earth added with the original molten iron Sulfur content increases; the appropriate control range of rare earth with the reduction of sulfur content of the original iron liquid narrow. Ductile iron in the amount of sulfur should have an upper limit, there should be a lower limit.