Integration technology of residue hydrotreating (RHT) and delayed coking (DC) was first proven to be an effective strategy to process high-sulfur residue oil while reducing the coke yield and simultaneously controlling the sulfur content of coke. Then, the evolution of sulfur species in the integration process was investigated by XPS, online TG-MS analysis, and atmospheric pressure photoionization FT-ICR MS. Finally, the essential effects of the RHT process on sulfur evolution were evaluated. The RHT process optimized the conversion of the refractory thiophenic sulfurs into sulfidic sulfurs as indicated by the increasing abundance of sulfidic sulfur during RHT, which thereby helped to reduce the sulfur content in coke. Moreover, RHT promoted the saturation of condensed-aromatic-ring structures of some refractory thiophenic sulfurs and thus promoted the thermal cracking of these sulfurs, and the resulting sulfurs with a smaller size thereupon directly evaporate into the liquid products, thus further reducing the sulfur content in coke.