Abstract: The surface porous Ti-hydroxyapatite(HA)/Ti-Ag gradient biocomposites were prepared by spark plasma sintering technology. The effects of different HA contents on the microstructure, interface bonding, surface pore characteristics, mechanical properties and in vitro biological activity of the surface porous Ti-HA/Ti-Ag composites were investigated. The results show that the matrix alloys of the composites are mainly consisted of α-Ti and Ti₂Ag phases. The surface porous layers are mainly consisted of α-Ti, HA phases and a few reaction phases of CaO, CaTiO₃, Ti₅P₃. A stable metallurgical bonding on matrix alloys and surface porous layers of the composites could be observed. With increasing of HA contents, the reaction phases of surface porous layers are increased and the bonding degree of interface is deterioration. The average porosity and pore size of surface layers are appeared in a slowly increasing trend. As a result, the average compressive strength and compressive elastic modulus of the surface porous Ti-HA/Ti-Ag composites are decreased. Therefore, the mechanical properties of the composites are reduced at higher HA contents. In vitro bioactivity tests show that lots of bone-like apatite are deposited on the surface porous Ti-HA/Ti-Ag gradient biocomposites after soaking in SBF for 7 days and the apatite formation ability is significant enhanced with increasing of HA contents.