The effects of BaO-ZnO-B2O3 (BZB) glass addition on the densification and dielectric properties of BaTi4O9 (BT4) have been investigated. With increasing BaO content in the BZB glass, the softening and melting points of the resulting BZB glass decrease, but the wetting between BZB and BT4 improves cosiderably. Although the densification temperature is reduced from 1300 degrees C for pure BT4 to 925 degrees C for BT4+BZB dielectric ceramics, the enhancement in densification becomes less significant with increasing BaO content in the BZB glass. The above result is attributed to a chemical reaction taking place at the interface of BZB/BT4 during firing, which becomes less extensive with increasing BaO content in the BZB glass. For the BZB glass with a BaO content in the range of 0-20 mol %, the resulting 90 vol% BT4 + 10 vol%. BZB microwave dielectric has a dielectric constant of 28-33, and a product (Q x f(r)) of quality factor (Q) and a resonant frequency (f(r)) of 15000-20000 GHz at 6.6 GHz.