Using molecular dynamics simulation with the modified analytic embedded-atom method (MAEAM), we calculated Gibbs free energy and surface free energy of bcc Mo with high melting temperature Tf, and further obtained the Gibbs free energy of its nanofilms. Based on the Gibbs free energy of nanofilms, we investigated the heat capacity of molybdenum nanofilms at constant pressure or at constant volume. The analysis reveals that the molar heat capacity of bulk sample is lower than that of the nanofilms, and the difference increases with the decrease of the film thickness. It is also observed that such size effect of Mo nanofilm is not really significant until the thickness is less than about 15—20nm. It is the surface atoms that determine the size effect on the thermodynamic properties of nanofilms. The difference between CV and CP of nanofilms is firstly analysed quantitatively and the calculated result for CV/CP varies linearly with T/Tf and relates directly to film thickness.