Abstract: A 1.7Mt/a residue hydrotreating unit of SINOPEC Changling Company, processed the feedstock with high S and low N, and high Fe and Ca content. The feed is difficult to hydrotreating and easy to cause pressure drop. The 2nd cycle of the unit adopted the 3rd generation RHT series catalysts developed by SINOPEC Research Institute of Petroleum Processing with an optimized catalyst grading. The commercial results demonstrate that the cycle life, processing capacity and mixing slag quantity increase obviously by the use of the 3rd generation RHT catalysts, compared with the second generation of RHT series catalyst, meanwhile the carbon residue conversion effect is better.