Residue deep hydrotreating (RDHT) process was developed by the Research Institute of Petroleum Processing (RIPP) to provide high quality feedstock for deep catalytic cracking (DCC) process. In this research work, the effects of RDHT process and reaction severity on heteroatom removal, hydrogen content increase, hydrocarbon composition improvement, and DCC product yields were studied. It was showed that the RDHT process can effectively reduce heteroatoms, increase hydrogen content and improve the hydrocarbon compositions, which can contribute to an increase of light olefins yield in DCC unit.