Recently, the rapid development of advanced communication systems increasingly strongly demands high-performance microwave dielectric ceramics in microwave circuits. Among them, Li 2 ZnTi 3 O 8 ceramics have been one of the most widely investigated species, due to its high quality factor, moderate firing conditions and low cost. However, the dielectric constants of the already reported Li 2 ZnTi 3 O 8 ceramics are fixed in a narrow range, limiting their wider applications. To adjust the dielectric constant of the Li 2 ZnTi 3 O 8 based ceramics, in this work Li 2 ZnTi 3 O 8 ceramics added with different amounts of Al 2 O 3 (0–8 wt%) were prepared by conventional solid-state reaction. The microstructure and microwave dielectric properties of the samples were investigated. Due to the addition of Al 2 O 3 , the sintering temperature of the ceramics would be increased somewhat. Some Al 3+ ions could substitute for Ti 4+ ions in Li 2 ZnTi 3 O 8 , and the added Al 2 O 3 would react with ZnO to produce a ZnAl 2 O 4 phase accompanying with the formation of TiO 2 phase, which would inhibit the growth of Li 2 ZnTi 3 O 8 grains. The dielectric constant of the finally obtained ceramics would be reduced from 26.2 to 17.9, although the quality factors of the obtained ceramics would decrease somewhat and the temperature coefficient of resonant frequency would deviate further from zero. [ABSTRACT FROM AUTHOR]