The 3D lattice structure is increasingly recognized in various applications due to its high porosity and excellent mechanical properties. However, fabricating these complex structures, especially using low-plasticity materials like titanium alloys, has posed significant challenges. The alternating pin-press method was successfully applied to produce titanium pyramidal 3D lattice core based on the high temperature forming mold. A brazing fixture was designed to protect the core during brazing, resulting in fully functional TC4 pyramidal 3D lattice structures. The fabrication structure achieved a compressive strength of 2.96 MPa and a relative compressive strength of 108.65 MPa at a relative density of 0.0272. Metallographic analysis revealed that forming at 800 ℃ resulted in equiaxed α phase with dispersed β phase, while brazing at 980 ℃, near the β-transformation temperature, led to coarse α and strip-like β phases. Experimental tests and finite element simulations demonstrated the variation in truss rod stiffness constant with geometry, identifying optimal truss angles of 33.4° for maximum flatwise compressive strength of 3.7 MPa and 44.8° for maximum relative compressive strength of 163.7 MPa. These findings offer valuable insights for the design of high-performance, low-density lattice structures in aerospace and related engineering fields.