Aiming at the lack of antibacterial activity in clinical applications of porous structures made of medical titanium alloy (Ti6Al4V) by laser additive manufacturing, Ti-based diamond composites were fabricated in this study using selective laser melting (SLM) technology, and a systematic investigation of their biological and mechanical properties was conducted. With parameters set at a laser power of 200 W, a scanning speed of 1200 mm/s, scanning hatch of 0.12 mm, Ti-based diamond composite materials and their porous lattice structures with good surface quality and uniform diamond distribution are successfully prepared. The biological performance tests showed that, through the antibacterial performance experiments using Staphylococcus aureus and Escherichia coli, and the in vitro compatibility experiments using mouse embryonic osteoblast precursor cells confirmed that the surface of samples from the proposed method have excellent antibacterial properties and high biocompatibility. Mechanical tests show that the compressive strength and elastic modulus of porous lattice structures with porosities of 50%, 60% and 70% were measured as 119.69±8.00 MPa and 3.09±0.07 GPa, 59.48±0.81 MPa and 1.84±0.06 GPa, 12.84±0.72 MPa and 0.68±0.03 GPa. The compression deformation mechanism of porous lattice structures with 50% and 60% porosity is characterized by fracture failure along a 45° inclined plane, whereas the structure with 70% porosity failed through layer-by-layer fracture. The Gibson-Ashby mathematical model was established to describe the relationship between porosity and mechanical properties, and is found to be highly compatible with the mechanical properties of human bone.