A three-step in situ polymerzition method was used to synthesize short-segmented block copolymers of poly(butylene succinate-co-butylene fumarate)/nano hydroxyapatite nanocomposites. The nanocomposites were characterized by H-1 NMR and Fourier transform infrared spectroscopy. The bond formed between nanohydroxyapatite and polymer led to a good particle dispersion which was studied using scanning electron microscopy (SEM). The thermal and crystallization properties of nanocomposites were calculated via differential scanning calorimetry and X-ray diffraction, indicating the formation of the complete crystals with two different sizes. Producing nanofiber from nanocomposites was done using the electrospinning method. According to SEM results, nanofibers were continuous and bead-free and those produced from nanocomposites had larger fiber diameter compared to the neat copolyester. In contrast to tensile strength, elastic modulus, hydrolytic degradability, and hydrophilicity of the resulted nanofiber which were increased with the nanoparticle, the elongation at break was slightly decreased.