Crystal structure exerts dominant influence on the microwave dielectric performance enabling satisfying the demands for 5G communication system. In this study, the Ti-doped Li3Mg2Nb1-xTixO6-x/2(x = 0.0-0.1) ceramics were prepared by the solid-state reaction procedure. Crystal structure refinement and microstructure analysis indicate pure phase with orthorhombic structure and homogeneous microstructure with grain size (~14 mu m). The relative permittivity was affected by the relative density, cell volume, and polarizability. TheQ x fvalue was dominated by the Nb-O bond energy and grain size. The tau(f)value was correlated with the NbO(6)octahedral distortion and Nb-O bond valence. Particularly, the composition (x = 0.04) exhibited remarkable microwave dielectric performance:epsilon(r) = 15.88,Q x f = 131 000 GHz and tau(f) = -26.8 ppm/degrees C, providing a promising candidate for millimeter-wave applications.