Abstract: The construction and application of the distributed computer system for the No. 4 Blast Furnace in Baotou Iron and Steel Corporation were described. The computer system consists of two parts:basic detection and control computers and process computers. The former is responsible for the sampling of real-time signals and the automatic control, while the latter accomplishes the data processing, the operation of expert systems, the prediction of the working status of the BF and the communication among computers.