Poly(ethylene sebacate) (PESeb) and PESeb/silica nanocomposites (PESeb/SiO2) were prepared by in situ polymerization from the direct esterification of ethylene glycol with sebacic acid in the presence of proper amounts of silica nanoparticles. The non-isothermal crystallization behavior of PESeb/SiO2 nanocomposites has been studied using different theoretical equations such as Avrami, Ozawa and combined Avrami and Ozawa equations. It is found that the addition of nanoparticles of SiO2 influenced the mechanism of nucleation and the growth of PESeb crystallites. Also, the nanocomposites show a higher Avrami value than the neat PESeb, implying a more complex crystallization configuration. Moreover, the combined Avrami and Ozawa equation can successfully describe the crystallization model under the non-isothermal crystallization. The crystallization activation energies, E (a), calculated from "Kissinger's equation" have shown that the synthesized PESeb/SiO2 nanocomposites have lower energy than the neat PESeb, reflecting the much lower energy barrier for the rapid heterogeneous nucleation.