High-dense titanium alloys with a 3D network core-shell structure of different N contents were synthesized successfully by means of spark plasma sintering of the nitrided titanium particles. The microstructure investigation shows that the core-shell structure with an obvious boundary within a grain is constructed in light of different solid solution levels of nitrogen in grain boundary and grain inner. The mechanical behaviors have been experimentally assessed through compressive testing. The compacts exhibit a much enhanced strength while retaining a reasonable ductility, which can be attributed to their novel core-shell structure. With an increasing N content as well as shell thickness, the strength increases and the ductility decreases, in accordance with the morphology observations.