Abstract: It is investigated to use additive L to intensify the thermal cracking of Sheng Li Vacuum Residue were tested on the lab-scale evaluating equipment. The result demonstrated that much higher liquid yields and much lower coke yields have been achieved by adding L additive. Increased the liquid product is mainly the VGO fraction and its composition is mainly above 3-ring or multi-ring aromatic hydrocarbons. Therefore, that indicates L accelerates the cracking of alkyl chain of polycyclic aromatic and bridge chain between polycyclic aromatic structures. Gas composition data showed that the contents of methane, ethane and ethylene decreased the contents of propane, propylene, butane and butylenes increased with the introducing of L. It indicated that L likely has changed the way of hydrocarbon thermal cracking.