Abstract: The effects of the category and content of cored materials on FFR(fume formation rate)were studied.The results show that cored materials can be divided into three kinds in which,the first one can enhance the FFR,the second one can lower the FFR,and the third one has no effects on the FFR.Different kinds of cored materials and its content have different effects on the FFR.FFR is enhanced to couple with the increasing of the contents of Na₂SiF₆.No obvious effects of the ilmenite on the FFR can be found.The FFR can be lowered greatly when the core perfect matches of metal powders and feldspar.It is propitious for lowering the FFR when increasing the content of feldspar in appropriate confine ment.