In order to improve the wear resistance of titanium alloy and broaden its application range, the ZrN modified layer was prepared on the surface of TA18 (Ti-3Al-2.5V) titanium alloy by double-glow plasma alloying technology (DGPA). The phase structure, micro-morphology and composition distribution of modified layers were analyzed by using GIXRD, SEM, EDS. The surface roughness, nano-hardness and elastic modulus of the modified layer were measured by using a roughness tester and a nano indenter. The tribological properties of TA18 substrate and ZrN modified layer under different loads were explored by using a ball-disk wear testing machine. The results indicate that the modified layers with dense and uniform surface structure and "island-like" characteristics, have no obvious defects such as holes and cracks. The surface roughness of ZrN modified layers is slightly increased and the phase composition is a coexistence of ZrN, ZrO2, TiN0.3, with obvious ZrN (111) preferred orientation. The total thickness of the modified layer is about 10 μm, with a ZrN layer of 3 μm, a Zr deposition layer of 4 μm and a Zr diffusion layer of 3 μm. The nano-hardness and elastic modulus of ZrN modified layers are 21.03 GPa and 258 GPa, respectively, which are 4.34 and 0.87 times higher than the matrix. The wear tests show that a large number of furrows exist on the surface of the wear scar and accompanied with obvious adhesion characteristics, and its wear mechanism is typical abrasive wear and adhesion wear. The ZrN modified layer has slight abrasive wear under the low load (330 g). An obvious O element aggregation and a small amount of adhesion characteristics appear in the wear scar area under the medium load (530 g) and high load (730 g), which reveals its wear mechanism is oxidative wear and adhesive wear. Meanwhile, there is no obvious peeling in the wear zone of the ZrN modified layer under different loads.