To investigated on the reasons for the fines increase with PCR, several analyses such as TGA, SEM and separation by heavy medium are carried out for blast furnace wet dust and fines obtained by coke sampling. The results show that the fines are composed of unburned pulverized coal and coke. The contribution of char and carbon contents in char and coke fines changes with coal combustibility. It is concluded that the origin of carbon source, coke or coal, can be discriminated by the relative intensity of graphite peak in XRD carbon analysis.