The sintering behaviors and dielectric properties of the Li2MgTiO4 ceramics at microwave frequency were investigated as a function of BaCu(B2O5) in this paper. The addition of BaCu(B2O5) dramatically decreased the sintering temperature of Li2MgTiO4 ceramics from 1250 to 900 °C. No secondary phase was detected and single phase Li2MgTiO4 with NaCl structure in the 1.0–4.0 wt% BaCu(B2O5) doped Li2MgTiO4 ceramics was confirmed, while a small amount of BaCu(B2O5) phase was found in the 8.0 wt% BaCu(B2O5) doped Li2MgTiO4 ceramics. No much deterioration of dielectric properties at microwave frequency of the BaCu(B2O5) doped Li2MgTiO4 ceramics sintered at 900 °C for 3 h occurs and favorable dielectric properties (εr = 15.8, Qf = 74,790 GHz and τf = − 24.3 ppm/°C) at microwave frequency were obtained for the Li2MgTiO4 ceramics with 4.0 wt% BaCu(B2O5) addition. Accordingly, such a favorable 4.0 wt% BaCu(B2O5)-doped Li2MgTiO4 ceramic might be a potential candidate material for LTCC applications.