Zn0.7Co0.3(Ti1-xSnx)Nb2O8(x=0.1，0.15，0.2，0.25，0.3，0.35) microwave ceramics were prepared by traditional solid-state reaction method. The influences of Sn substituted for Ti on the phase constitution crystal structure and microwave dielectric properties of Zn0.7Co0.3(Ti1-xSnx)Nb2O8 ceramics were also discussed.The XRD patterns revealed the main phase of ZnTiNb2O8 and little substitution content of Zn0.17Ti0.5Nb0.33O2.With further substitution of Sn,the lattice constant, volume and density of the ceramics increased, the ceramics structure also became tight showed by SEM.Tremendous improvement of Q×f value while a declining trend of εr and τf were obtained with increasing x value.Appropriate substitution value(x=0.35) would conduct excellent microwave dielectric properties(εr=30.5,Q×f=46 973GHz,τf=-45.4×10-6/℃) sintered at 1 080 ℃.