(ZnNb2O6-Zn3Nb2O8)-Sb2O3(ZZS) ceramics were fabricated by the conventional ceramic processing.The effects of the contents of Sb2O3 on the microstructures and dielectric properties of ZZS ceramics were investigated. The results showed that Sb2O3 accelerated the sintering of ZnNb2O6-Zn3Nb2O8 ceramics.No other phase was observed in the ceramics except the two main phases of ZnNb2O6 and Zn3Nb2O8.It was shown that Sb3+could change into Sb5+ and replace Nb5+ or Zn2+to form the substitutional solid solution.The dielectric constant (εr) increased firstly and then decreased with the increase of the content of Sb2O3,but maintained between 23 and 25,while the dielectric loss has increased slightly.At the microwave frequency range,the dielectric constant of 0.7ZnNb2O6-0.3Zn3Nb2O8 decreased slightly and the value of Q×fincreased firstly and then decreased with the content of Sb2O3.The ceramic with the composition of 1% of Sb2O3 showed the optimal dielectric properties of εr=22.88 and Q×f=38 871 GHz.