Press process was performed in order to toughen HA/PLLA bio-composite material. Mode I fracture properties and bending mechanical properties of forged and unforged HA/PLLA were then evaluated to assess the effect of press process on these properties. FE-SEM was also used to characterize the toughening mechanism due to press. Testing results showed that the bending strength and modulus slightly increased due to press; on the other hand, the bending absorbed energy and the mode I fracture property dramatically improved. FE-SEM observation of the fracture surfaces showed that ductile deformation and fracture of PLLA fibrils were enhanced and in addition, interfacial cohesion strength was improved. These microstructural modifications appear to result in the toughness improvement.