Samples of xBiFeO 3 -(1 -x)BaTiO 3 (x = 0, 0.02, 0.04, 0.06, 0.07 and 0.08) were synthesized by solid state reaction technique and sintered in air in the temperature range 1,220-1,280°C for 4 h. X-ray diffraction data showed that 2-8 mol% BiFeO 3 can dissolve into the lattice of BaTiO 3 and form single perovskite phase. The crystal structure changes from tetragonal to cubic phase at room temperature when 8 mol% of BiFeO 3 was added into BaTiO 3 . Scanning electron microscope images indicated that the ceramics have compact and uniform microstructures, and the grain size of the ceramics decreases with the increase of BiFeO 3 content. Dielectric constants were measured as functions of temperatures (25-200°C). With rising addition of BiFeO 3 , the Curie temperature decreases. For the sample with x = 0.08, the phase transition occurred below room temperature. The boundary between tetragonal and cubic phase of the BiFeO 3 -BaTiO 3 system at room temperature locates at a composition between 7 and 8 mol% of BiFeO 3 . The diffusivity parameter c for compositions x = 0.02 and x = 0.07 is 1.21 and 1.29, respectively. The relaxor-like behaviour is enhanced by the BiFeO 3 addition.