Effect of mixing process on the fracture behavior of HA/PLLA Composites were investigated. Fracture toughness values of HA/PLLA composites prepared under different mixing time and rotor speed were measured. The fracture surface morphology was also examined by scanning electron microscopy. It was found that the fracture toughness of HA/PLLA composite decreases due to decrease of ductile deformation of PLLA matrix and debonding of interfaces with increase of the rotor speed and mixing time. Effect of mixing process on neat PLLA was also assessed, and it was found that the fracture toughness of PLLA decreases due to such pocess. Disappearance of multiple craze formation and thermal degradation were found to be the primary mechanisms of the toughness degradation.