Ti6Al4 V (Ti64) lattice structures manufactured using selective laser melting (SLM) have been used in fields such as aerospace and medical science due to their exceptional light weight, corrosion-resistant capability and biocompatibility. In this study, the mechanical properties of octahedral-type Ti64 lattice structures under quasi-static loading conditions was investigated. The initial stiffness, ultimate strength and ductility of the structures with different aspect ratios were evaluated and compared using experiments and quasi-static finite element analysis (FEA). The results demonstrated that the experimental data and FEA were in good agreement. The initial stiffness and strength of the octahedral lattice structures improved significantly as the strut aspect ratios decreased; however, the poor ductility evident in all the samples showed no obvious relationship to the aspect ratios, which means that the geometrical sizes had little effect on the brittle behaviour of the Ti64 lattice structures fabricated using SLM.