The purpose of this study was to evaluate the behavior of nano-hydroxyapatite/ poly(D,L)lactide (n-HA/PDLLA) composite in vivo. The composite rods containing about 40wt% n-HA and control HA rods with a diameter of 2mm and a length of 6mm were implanted into the femora of 16 New Zealand rabbits. Composite wafers with a diameter of 5mm and a thickness of 1mm were implanted into the dorsal subcutis of 18 Wistar Albino rats. After definite intervals, the histological analysis was completed by light microscopy and the degradation behavior was observed by scanning electron microscopy. The histological analysis showed no obvious difference between n-HA /PDLLA composite and pure HA that had good biocompatibility and osteoconductivity. SEM analysis of the surface and cross section of the samples showed that the degradation of the composite started from surface, then into the inner gradually and formed multiple pores at surface. The pore size and porosity gradually increased along with time and a porous network may be formed.