The invention belongs to the technical field of ceramic materials, and discloses a high-Q-value lithium titanate-based microwave dielectric ceramic material and a preparation method thereof. The preparation method comprises the following steps: subjecting Li2CO3 and TiO2 to burdening, ball milling, drying and sieving according to a stoichiometric formula Li2TiO3 and then performing presintering at a temperature of 800-1000 DEG C; adding an M doping agent, carrying out ball milling, drying, sieving and granulating successively, and conducting pressing to obtain a green body; and sintering the green body at a temperature of 1100-1180 DEG C. The chemical formula of the obtained high-Q-value lithium titanate-based microwave dielectric ceramic material is Li<2>TiO<3+x>M, wherein M is Li2CO3, MgO, LiF, MgF2 or MgO + LiF, and x is equal to 0.6 wt.%-3.6 wt.%. According to the invention, different types of dopants are introduced into Li2TiO3, so the sintering characteristic of microwave dielectric ceramic is improved, and the defect that the Qf value of pure Li2TiO3is low is overcome; the produced material has a high quality factor and a moderate dielectric constant; a preparation process is simple; and microwave dielectric devices manufactured, researched and developed on the basis of the material have wide application prospects.