Using the invention patent technology (patent number ZL2005 1 0131175.7), the impact on environment in ductile iron production was studied. By using the environmentally friendly and adjustable spheroidizing equipment, the spheroidization can proceed in a completely closed state. The smoke with the spheroidization is eliminated just as the production of inoculated cast iron. The pressure in the ladle can be automatically adjusted from 0KPa to 8.62KPa and the absorption rate of elements is improved. Without sacrificing the spheroidizing level and mechanical properties, the amount of added nodularizer can be decreased by 0.2%-0.5%. Saving the costs and protecting the environment.