•This work revealed the law of gas sulfides release during the reduction process of blast furnace raw materials.•The precipitation of sulfur during the reaction of coke and sinter in reducing atmosphere was divided into two stages.•Low temperatures favored the generation of H2S, while high temperatures promoted the generation of COS. Understanding the transformation behavior of sulfides in the blast furnace raw materials during the ironmaking process is crucial for controlling the form and emission of gaseous sulfides in the blast furnace top gas. This study investigates the reactions of coke and sinter at different reducing atmosphere ranging from 200 °C to 1000 °C by using of thermogravimetry and mass spectrometry (TG-MS). Additionally, thermodynamic theoretical calculations were performed to enhance the understanding of the reaction behavior. The results showed that the mixed sinter and coke started to generate H2S at 100 °C under the mixed H2-CO atmosphere and reached the peak between 350 and 400 °C. With the increase of H2 concentration, the peak temperature of H2S generation initially decreased and then increased, with the lowest peak temperature observed under a 50% H2-50% CO atmosphere. Furthermore, COS generation started around 300 °C and reached its peak at approximately 800 °C. The peak content of COS generation increased as the CO concentration. Low temperatures favored the generation of H2S from the mixed sinter and coke, while high temperatures were conducive to the generation of COS.