Nano-hydroxyapatite reinforced poly(vinyl alcohol) gel(nano-HA/PVA gel) composites has been proposed as a promising biomaterial,especially used as an articular cartilage repair biomaterial.In this paper,nano-HA/PVA gel composite was prepared by in situ synthesis method and incorporation with freeze-thaw cycle process.The microstructure and morphology were investigated by X-ray diffraction,TEM,SEM and FTIR.The results showed that the size of HA particles synthesized in PVA solution was on the nanometer scale.Both the size and crystallinity of HA particles synthesized in PVA solution decreased compared with that of HA synthesized in distilled water.The nano-HA particles were distributed in PVA matrix uniformly due to the effect of PVA solution as a dispersant while low content of HA particles in the composites.On the contrary,with high content of nano-HA particles in the composites,the particles tended to aggregate.The result of FT-IR analysis indicated that the chemical bond between nano-HA particles and PVA matrix existed.The conformation and degree of tacticity of PVA molecule changed because of the addition of HA particles.Furthermore,the interfacial strength of the composites was improved due to the interaction between nano-HA particle and PVA matrix and this was beneficial to improving the mechanical properties of the composites. Nano-hydroxyapatite reinforced poly (vinyl alcohol) gel (nano-HA / PVA gel) composites has been proposed as a promising biomaterial, especially used as an articular cartilage repair biomaterial. In this paper, nano-HA / PVA gel composite was prepared by in situ synthesis method and incorporation with freeze-thaw cycle process. The microstructure and morphology were investigated by X-ray diffraction, TEM, SEM and FTIR. The results showed that the size of HA particles synthesized in PVA solution was on the nanometer scale. Both the size and crystallinity of HA particles synthesized in PVA solution decreased compared with that of HA synthesized in distilled water. The nano-HA particles were distributed in PVA matrix uniformly due to the effect of PVA solution as a dispersant while low content of HA particles in the composites. On the contrary, with high content of nano-HA particles in the composites, the particles tended to aggregate. The result of FT-IR analysis indicated that the chemical bond between nan o-HA particles and PVA matrix existed. The conformation and degree of tacticity of PVA molecule changed because of addition of HA particles. Still more, the interfacial strength of the composites was improved due to the interaction between nano-HA particle and PVA matrix and this was beneficial to improving the mechanical properties of the composites.