CaCu2.8Nb0.2Ti4-xNixO12　(x=0.1,　0.2,　0.3)　and　CaCu3Ti4O12　ceramics　were　successfully　fabricated　through　the　solid-state　reaction　method.　All　the　samples　were　methodically　examined　by　X-ray　diffraction　(XRD),　scanning　electron　microscopy　(SEM),　impedance　and　dielectric　properties　measurements.　XRD　analyses　verified　the　constitution　of　a　cubic　perovskite　structure　with　Im-3　space　group.　The　average　grain　size　of　CaCu3Ti4O12　ceramics　reduced　with　Ni　and　Nb　ions　doping,　especially　decreased　significantly　with　the　increase　of　Ni　content.　Compared　with　un-doped　CaCu3Ti4O12,　Ni　and　Nb　ions　doped　CaCu3Ti4O12　ceramics　presented　greatly　enhanced　dielectric　constant　range　from　102　Hz　to　106　Hz,　illustrating　the　Ni　and　Nb　ions　have　great　influence　on　improving　the　dielectric　constant.　The　CaCu2.8Nb0.2Ti3.8Ni0.2O12　sample　achieves　the　highest　dielectric　constant,　possesses　the　lowest　dielectric　loss　and　acquires　the　largest　grain　boundary　resistance　in　the　doped　samples.　Therefore,　it　has　optimal　dielectric　performance.　©　Published　under　licence　by　IOP　Publishing　Ltd.