Abstract: The CaCu₃Ti₄O₁₂ ceramics doped by Eu₂O₃ with different dopant contents（w% x=0,0.2%,0.5%,1%） are prepared by the traditional solid-state reaction method.SEM,XRD and Agilent 4294A Precision Impedance Analyzer are used to measure the phase structure,the morphology,dielectric properties and the ac resistivity of the samples.The results show that the crystal structures of CCTO doped by Eu₂O₃ are similar to that of pure CCTO.But Eu₂O₃-dopping can decrease the relative content of crystals in the CCTO ceramics with identical component and the average grain size and can also deter the formation of Cu-enriched phase in the grain boundary.The second phases of CuO、TiO₂ and CaCO₃ are present in the XRD pattern of pure CCTO and disappear in that of the samples doped by Eu₂O₃.In addition,it has been found that the dielectric properties of CCTO ceramics are greatly associated with the relative content of crystals in the CCTO ceramics with identical component,the average grain size and Cu-enriched phase in grain boundary.Eu₂O₃-dopping can improve the frequency and temperature stability of dielectric properties of the materials.The better improvement to the dielectric properties is achieved by doping 0.2w% and 0.5%of Eu₂O₃.The effect of microstructure changing on the dielectric properties after being doped by Eu₂O₃ has been well confirmed by the ac resistivity of samples measured at 40Hz and 3.5MHz respectively.