Effect of glass addition on the low-temperature sintering and microwave dielectric properties of $BaTi_4O_9$-based ceramics were studied to develop the materials for the functional substrate of low-temperature co-fired ceramics. When 10 wt% of glass was added, sufficient densification was obtained and the relative density more than 98% was reached at the sintering temperature of$875{circ}C$. The microwave dielectric properties were k=32, Q＊f=9000 GHz, ${ au}_f$=10 ppm/${circ}C$. As the amount of glass increased, phase decompositions from $BaTi_4O_9;to;BaTi_5O_{11};and;Ba_4Ti_{13}O_{30}$ was observed.