Density functional theory calculations on level of B3LYP functional and 6-31 G** basis set are carried out on glycerol esterification reactions. The most stable structures of the reactants, intermediates and products are located by considering a large amount of conformers. The thermodynamics is discussed in terms of the calculated reaction Gibbs free energy. The glycerol esterification with acetic acid is found to be thermodynamically resisted, while its esterification with acetic anhydride is preferable with significantly exothermal property. This agrees well with experiments. The proposed process art has been experimentally and theoretically proved to be with low production costs and high head product selectivity. (C) 2009 Elsevier B.V. All rights reserved.