AbstractPoly(amino acid)/nano hydroxyapatite (PAA/n‐HA) bioactive composite was prepared by in situ melting polymerization. The composition, structure and morphology as well as glass transition temperature (Tg), dynamic mechanical properties of the PAA/n‐HA composite were characterized by infrared spectrometer, X‐ray diffractometer, X‐ray photoelectron spectroscopy, scanning electron microscope, differential scanning calorimeter, and dynamic mechanical analyzer. The results indicated that the n‐HA particles were uniformly distributed into PAA matrix and some interactions were found at the interface between PAA and n‐HA, and the crystallinity of PAA in the composite decreased with the increase of n‐HA content. The Tg and storage modulus of the composite increased with increasing n‐HA content, demonstrating that the n‐HA content had obvious effects on the crystallization kinetic parameters and thermo properties of the PAA/n‐HA composite. In addition, the n‐HA amount had evident effects on the degradation of the PAA/n‐HA composite in phosphate buffered saline (PBS), and the weight loss ratio of the composite decreased with the increase with n‐HA content. The pH value of the medium was stable around 7.40 after the composite immersion into PBS for 8 weeks. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012