The pyrolysis of 5-HMF was investigated using density functional theory methods at B3LYP/6-31G++(d, p) level. Two possible pyrolytic pathways were proposed and full optimization of the energy gradient for the structures of reactants, products, intermediates and transition states of various reactions was implemented. The standard kinetic parameters in each reaction pathway were calculated and the formation and evolution mechanism of main pyrolysis products were analyzed. Bond dissociation energies calculation results show that the bond dissociation energy of CH3—OH of 5-HMF is the lowest and the order of all kinds of bond dissociation energy is CH3—OH