Chemistry is no longer a pure experimental science. Theoretical calculations and chemical experiments can be used to study the properties of compounds and chemical reactions from different perspectives. Now, calculation is an important branch of chemical research. In this manuscript, through a specific calculation study on the mechanism of CO2 functionalization reduction reaction of aniline, the basic methods and processes of quantum calculation are introduced and some reaction details that are easily overlooked or cannot be discovered during the experimental process are discovered by analyzing the calculation results.