Abstract: The Fe/SiO₂ in Slag model of copper flash smelting process, which has the net-structure of 3 in-put, single out-put data, and the membership functions are 5 3 5, was developed based on Adaptive Fuzzy Inference System and the practical data from one Copper smelter. The results indicate the average absolute error of train samples is 0.0055 and the relative error percentage is 1.4%. The simulation results show that the average absolute error is 0.028%, and the relative error percentage is 2.9%. It means that the simulative results accord to the practical data. Thus, the model has good reference value on process optimized control of copper smelting. It also can be used in industrial online control to replace the model of static mixture.