Abstract: A new cover-type circulating mechanical vacuum refining equipment has been built in Jingye Iron and Steel Co.，Ltd. to produce ultra-low carbon steels，such as non-oriented silicon steel and industrial pure iron. In the control link，ultra-low carbon steels such as industrial pure iron of w(C)≤20×10-6 were smelted from aspects of carbon temperature coordination in converter tapping，development of decarbonization process of cover-type circulating mechanical vacuum refining device and control of carbon content of raw materials. The results showed that in the production process of ultra-low carbon steel，the carbon content of converter tapping should be controlled between 0.025% to 0.040%. Under the condition of vacuum oxygen blowing，the carbon content of converter tapping could be relaxed to less than 0.060%. Carbon and temperature should be coordinated at the end of converter tapping，and deoxidizing alloys containing aluminium or silicon should be strictly prohibited during tapping. Vacuum decarburization needed to control vacuum degree in decarburization period and gas flow driven by bottom blowing of steel ladle in stages. The carbon content of alloys and refractory materials used should be as low as possible.

Key words: cover circulating mechanical vacuum, ultra-low carbon, vacuum refining