Abstract: In order to optimize the thermal parameters of BF gas sludge and realize the good separation of iron and zinc from the sludge, the single factor experiment of heating self reduction of the sludge pellet and that of factor optimization design by BBD (Box-Behnken Design) method in response surface were carried aiming at the problem difficult to separate and recover iron and zinc from the sludge. The metallization rate of iron and that of zinc are used as the evaluation index for the separation of iron and zinc. The results show that the influence of thermal parameters on the reduction and separation of iron and zinc oxides are time > temperature > pelleting pressure; the optimized conditions are1299.95℃, 47.05 min and 8 MPa of pelleting pressure. It is obtained by the optimization test of thermal parameters designed by BBD method that the metallization of iron and zinc reach to 94.67% and 96.08%, respectively, and iron is mainly retained in pellets in the form of metallic iron and Zinc enters into the dust as a gaseous element zinc and then oxidized to ZnO dust. Good separation of iron and zinc is achieved.