This study measured the contents of the ionic and elemental constituents, and the chemical compounds containing in windbox (WB) dusts collected from a commercial iron ore sintering plant, then the results were used to identify possible PCDD/Fs formation pathways in the WB. We found that the abundance in both KCl and NaCl may provide a suitable condition for de novo synthesis of PCDD/Fs in the WB. Al, Fe, K, Ca, and Pb were the top five contents in WB16 dusts, but the co-existence of the above five metal contents warrants the need for further investigation on their roles in PCDD/F formation processes in the future. Although a low concentration of Cu was detected, it might be of importance to PCDD/Fs formation inside the WB. A total of 29 chemical compounds were identified. Among them, several oxygenated organic compound might be associated with PCDD/F formations at the beginning stage, but the roles of aromatic oxygenates on the formation of PCDD/Fs required further investigation. Finally, possible de novo synthesis pathways of PCDD/Fs were proposed based on the above findings. However, the above pathways are required further laboratory studies for validation before possible formation suppression approaches can be determined.