A novel series of temperature stable Li3Mg2NbO6–xTiO2 ceramics were prepared by the conventional solid-state route. The effects of TiO2 addition on the sintering behavior, phase composition, microstructure and microwave dielectric properties were investigated systematically. The dense microstructure could be obtained in low TiO2 content (x=0.1) samples sintered at 1100 °C. The dielectric constant εr was attributed to the bulk density and TiO2 content. The variation in Q×f values is related to the bulk density, and improved values could be obtained for Li3Mg2NbO6–0.1TiO2 ceramics. The quality factor (Q×f) had a maximum for x=0.1 and the temperature coefficient of resonant frequency (τf) value shifted towards positive direction with the increase of TiO2 addition. Notably, Li3Mg2NbO6–0.1TiO2 ceramics sintered at 1100 °C possessed excellent microwave dielectric properties: εr=15, Q×f =74,000 GHz(9.93GHz), τf= −3.4 ppm/°C, which made the ceramics as promising low loss and temperature stable candidates for millimeter-wave applications.