Herein, Li1.0Nb0.6Ti0.5O3 + x wt% BaCu(B2O5) (0 ≤ x ≤ 0.8) ceramics were synthesized via the traditional solid-state reaction method. The sintering behavior, phase, Raman spectra, microwave dielectric characteristics, and chemical compatibility with Ag of the Li1.0Nb0.6Ti0.5O3 + x wt% BaCu(B2O5) samples were comprehensively analyzed. The results show that doping the Li1.0Nb0.6Ti0.5O3 ceramics with BaCu(B2O5) can not only reduce the sintering temperature from 1100 °C to 950 °C but also effectively improve the density and quality factor (Q×f) of the Li1.0Nb0.6Ti0.5O3 samples. Additionally, Li1.0Nb0.6Ti0.5O3 + 0.4 wt% BaCu(B2O5) samples, which were sintered at 950 °C for 4 h, exhibit excellent microwave dielectric properties (εr= 61.4, Q×f = 6423 GHz, and τf= 27.5 ppm/°C) and excellent chemical compatibility with Ag, which makes these ceramics potential candidate materials in the low-temperature co-fired ceramic technology.