With data of silicon content in hot metal collected respectively from No. 6 blast furnace of Baotou Steel, No. 7 blast furnace of Handan Steel and No.1 blast furnace of Laiwu Steel as sample spaces, quantitative analysis was employed to identify the multi-fractal characteristics of silicon content series. The long term trend of silicon content series was removed by performing multi-resolution analysis and the multi-fractal characteristics of the remaining part was analyzed. Comprehensive and quantitative details of the partial fluctuant singularity and fluctuant singularity at different levels are displayed through computation of generalized Hurst index, scaling function and multi-fractal spectrum. Simulation results proved that the fluctuation of silicon content series from 3 different blast furnaces showed significant multi-fractal characteristics, which is far from sufficient to be described by a single Hurst index or box dimension.