About 10 billion tons of virgin plastics have been produced as of 2022. The effective way to eliminate and utilize plastic waste is by destructive thermal treatment, such as combustion, pyrolysis, gasification, hydrocracking, etc. Through gasification, plastics are mostly converted into gas products (H2, CO, CH4, CO2, etc.), of which syngas (H2 and CO) can be widely used for downstream applications. Catalytic reforming of plastic was widely researched to produce syngas, but the coke deposition had a great influence on catalyst activity and syngas selectivity. In chemical looping gasification (CLG), the gaseous agent is replaced with the lattice oxygen in the oxygen carrier (OC), which can effectively decrease the deposited coke due to the reduction and oxidation cycles of OC. However, there are limited reports on the CLG of plastic. 30%NiO/Al2O3 (30NA) as the OC was used in this work for the CLG of Polypropylene (PP). Four reaction modes (Type a-d) with different heating rates and feeding methods of PP and 30NA during the gasification stage were studied to illustrate their effect on the gaseous product. Compared with the blank experiments (SiO2 as the OC), a significantly improved syngas yield was obtained when using 30NA. The highest syngas yield and carbon conversion were obtained for Type-a at 65 mmol/g and 65%, respectively, which was owing to the good mixing of the samples and a stronger oxygen supply capacity in Type-a. In addition, a syngas selectivity of 80% was achieved for Type-a.