Abstract: To evaluate the properties of mesoporous nano hydroxyapatite (MHA)/poly(L-lactide) (PLLA) composites, MHA was synthesized with cetyltrimethylammonium bromide (CTAB) as template. MHA/PLLA porous scaffold composites with different contents of nano particles were prepared using solution phase separation and particle-leaching method, and the compressive property and micro-structure of quenching fracture cross-sections were evaluated. And then MHA/PLLA composite films were prepared using solvent casting method and the tensile property and micro-structure of tensile fracture cross-sections were evaluated. FTIR, XRD, TEM and N₂ adsorption test results show that the prepared MHA has typical crystal structure, mesoporous structure and higher specific surface area. The mechanical test show that the MHA/PLLA porous scaffold composites with filler content of 1%, 5% and 10% exhibit increasing compressive strength under 10% compression deformation with the filler content increasing, and are 37.0%、67.7% and 144.7% higher than those of corresponding content of nano hydroxyapatite (HA)/PLLA porous scaffold composites, respectively. With the filler content of 5% and 10%, the tensile strength of MHA/PLLA composite films are 38.7% and 46.1% higher than those of HA/PLLA composite films, the strength modulus are 35.4% and 14.5% higher, respectively. And MHA/PLLA composite films possess higher elongation at break. With the filler content of 1%, 5% and 10%, the elongation at break are 91.3%, 79.7% and 96.1% higher than those of HA/PLLA composite films, respectively. FESEM photographs show that the distribution of filler particles in MHA/PLLA porous scaffold composites or composite films is more uniform than that in HA/PLLA when the filler content is higher. The results indicate that, compared with HA/PLLA composites, better mechanical property and more evenly MHA distribution in PLLA matrix are obtained as the increasing content of MHA.