To enhance the present comprehension of lignocellulose pyrolysis, it is necessary to incorporate physicochemical information into kinetic models, which can be acquired through the use of computational chemistry techniques. Particularly, quantum chemistry modelling can give many details at the atomic/molecular level. It is usually performed to simulate the pyrolysis of the individual principal biomass components, interactions within/between these materials, and catalytic pyrolysis with various catalysts. On the basis of the theoretical models in quantum chemistry modelling, geometric structures, transition states, intermediates, corresponding electron transfers, orbital interactions, energetics, and other important information involved in the pyrolysis process can be obtained. Benefiting from the advancement of theoretical methods and computer hardware, quantum chemistry modelling is playing increasingly important roles in the lignocellulosic biomass pyrolysis mechanism studies.