The effects of the filler content and the filler size on the crystallization and melting behavior of glass bead-filled low-density polyethylene (LDPE) composites have been studied by means of a differential scanning calorimeter (DSC). It is found that the values of melting enthalpy (Delta H-c) and degree of crystallinity (x(c)) of the composites increase nonlinearly with increasing the volume fraction of glass beads, phi(f), when phi(f) is greater than 5%; the crystallization temperatures (T-c) and the melting temperatures (T-m) of the composites are slightly higher than those of the pure LDPE; the effects of glass bead size on x(c), T-c, and T-m are insignificant at lower filler content; but the x(c) for the LDPE filled with smallejr glass beads is obviously greater than that of the filled system with bigger ones at higher phi(f). It suggests that small particles are more beneficial to increase in crystallinity of the composites than big ones, especially at higher filler content. In addition, the influence of the filler surface pretreated with a silane coupling agent on the crystallization behavior are not too outstanding at lower inclusion concentration.