The B 2 O 3 -doped 5Li 2 O–1Nb 2 O 5 –5TiO 2 composite microwave dielectric ceramics prepared by conventional and low-temperature single-step reactive sintering processes were investigated in the study. Without any calcinations involved, the Nb 2 O 5 mixture of Li 2 CO 3 and TiO 2 was pressed and sintered directly in the reactive sintering process. More uniform and finer grains could be obtained in the 5Li 2 O–1Nb 2 O 5 –5TiO 2 ceramics by reactive sintering process, which could effectively save energy and manufacturing cost. And relatively good microwave dielectric properties of ɛ r =41, Q×f=9885GHz and τ f =43.6ppm/°C could be obtained for the 1wt.% B 2 O 3 -doped ceramics reactively sintered at 900°C.