Integrated iron and steel industry is the main source of polychlorinated dibenzo-p-dioxins (PCDDs) and dibenzofurans (PCDFs) or, more briefly, of dioxins. These mainly arise from sintering process, yet also other operations, such as blast furnace, basic oxygen furnace and electric arc furnace. In this study, it is verified in how far the fly ash collected from above-mentioned operations could contribute to PCDD/Fs as well as other organic pollutants (polychlorinated biphenyls (PCBs), chlorobenzenes (CBzs) and polyaromatic hydrocarbons (PAHs)) emissions. The experiments were conducted using a lab-scale vertical tube reactor and target pollutants in off-gas and residue were collected together for analysis. The experiments results show that sintering fly ash generates much more above-mentioned pollutants, especially for PCDD/Fs and dioxin-like PCBs, which are 2–3 orders of magnitude higher than other four fly ash samples. Homologue group profiles of target pollutants also show significant difference. Both of PCBs and CBzs are dominated by low-chlorinated compounds in all samples, however, STA sample generated much more high-chlorinated compounds. In addition, the correlations between various target pollutants built from all samples show that PCDDs are clearly related to the low-chlorinated PCBs and CBzs, and PCDFs are strongly related with high-chlorinated PCBs and CBzs. Within each homologue group of PCDD/Fs, the isomer signature also has been further scrutinized, with special emphasis on the seventeen 2,3,7,8-substituted PCDD/Fs, as well as on the seven PCDD-congeners and two TCDF usually associated with chlorophenol precursor routes, with the purpose to throw more light on the mechanism of PCDD/Fs-formation.