La1-xZnxTiNbO6-x/2 (LZTN-x) ceramics were prepared via a conventional solid-state reaction route. The phase, microstructure, sintering behavior, and microwave dielectric properties have been systematically studied. The substitution of a small amount of Zn2+ for La3+ was found to effectively promote the sintering process of LTN ceramics. The corresponding sintering mechanism was believed to result from the formation of the lattice distortion and oxygen vacancies by means of comparative studies on La-deficient LTN ceramics and 0.5 mol% ZnO added LTN ceramics (LTN+0.005ZnO). The resultant microwave dielectric properties of LTN ceramics were closely correlated with the sample density, compositions, and especially with the phase structure at room temperature which depended on the orthorhombic-monoclinic phase transition temperature and the sintering temperature. A single orthorhombic LZTN-0.03 ceramic sintered at 1200 degrees C was achieved with good microwave dielectric properties of epsilon(r)similar to 63, Qxf similar to 9600 GHz (@4.77 GHz) and (f) similar to 105 ppm/degrees C. By comparison, a relatively high Q x f similar to 80995 GHz (@7.40 GHz) together with epsilon(r similar to)23, and (f) similar to-56 ppm/degrees C was obtained in monoclinic LTN+0.005ZnO ceramics sintered at 1350 degrees C.