Based on the algorithm of Kolmogorov entropy presented by Grassberger and Procac cia, as the time series data of silicon content in molten iron of No.1 BF at Laiwu and No.6 BF at Linfen Iron and Steel Group Cos. to be as samples, their Kolmo gorov entropy are computed to be (01453±00151)nats·h-1-1 an d (01553±00140)nats·h-1-1, and the time scales of forecasti ng in both BFs are estimated to be about 688 and 644h respectively. Since the value of Kolmogorov entropy is finite and positive, there is chaos in both b last furnace ironmaking processes, and the idea that Kolmogorov entropy may be u sed to judge the condition of BF is presented.