Abstract: Troubled by the intensified problem of energy and environment, researchers gradually focus on the development of engine performance. The aim of investigating chemical reaction mechanism on combustion is to predict and control the combustion processes for enhancing combustion efficiency, controlling flame stability and reducing emission. Analogy is a way to predict reaction rate constants of large fuel molecules for establishing the combustion reaction model. However, this would cause a large difference compared with the experiments. To better apply large fuel molecule on engine, it is necessary to study high-level chemical kinetics. However, there is a relatively huge computational challenge using prevalent high-level electronic structure method (CCSD(T)/CBS and QCISD(T)/CBS) to deal with the large molecules. Based on the difficulties mentioned above, this paper mainly focused on the current high-level quantum chemistry calculation methods which can be used in large molecule systems, and made a comprehensive introduction of ONIOMQCISD(T)/CBS:DFT method. Not only does this method provide an accurately computational and available approach for studying large fuel molecules, also the reliable thermochemical data from the method is useful for the high-level chemical kinetics calculation.