To meet the requirements of high-frequency wireless communication, microwave dielectric ceramics of (1-x)MgNb2O6- xCaTiO3 (x=0, 0.02, 0.04, 0.08, 0.12, and 0.16) with a near-zero temperature coefficient were prepared by a solid-state method. The effect of CaTiO3 addition on the microstructure and dielectric properties of MgNb2O6 was investigated, and the formation and sintering behavior of each phase were analyzed. The results show that a proper addition of CaTiO3 can promote the sintering of MgNb2O6 and reduce its sintering temperature. Based on the X-ray diffraction analysis, CaTiO3 can react with MgNb2O6 to form CaNb2O6, Ti8O15, and Ti2Nb10O29 at a high temperature. Increasing the proportion of CaTiO3 reduces the quality factor Q×f, but increases the dielectric constant εr and frequency temperature coefficient τf. When the addition amount (x) of CaTiO3 is 0.16, the sample has the optimum microwave dielectric properties after sintering at 1 250 ℃ for 4 h (i.e., εr=21.6, Q×f =86 601 GHz, and τf = -7.3×10-6/℃).