With the aim of minimizing dioxin formation in industrial-scale plants, incinerator facilities of the twin interchanging fluidized-bed type were studied for the major factors influencing the dioxin level. A statistical model was derived based on multiple regression analysis of experimental data. It was found that the toxic equivalency level of dioxins is strongly positively correlated with fly ash copper and moderately with flue gas Oz content, and strongly negatively correlated with fly ash chlorine and weakly with carbon content.