The structures, Curie temperature, dielectric relaxor behaviors, ferroelectricity, ferromagnetism, and magnetocapacitance of the (1-x)Ba0.70Ca0.30TiO3-xBiFeO(3) [(1-x)BCT-xBF, x=0-0.90] solid solutions have been systematically investigated. The ceramics have coexisted tetragonal (T) and orthorhombic (O) phases when x0.06, coexisted pseudocubic (PC) and O phases when x=0.065, coexisted cubic and O phases when 0.07x0.12, PC phase when 0.21x0.42, coexisted T and rhombohedral (R) phases when 0.52x0.70, and R phase when x0.75. Significantly, composition-dependent microstructures and Curie temperature are observed, the average grain size increases from 1.9m for x=0, reaches 12.0m for x=0.67, and then decreases to 1.3m for x=0.90. At room temperature, the ceramics with x=0.42-0.70 show piezoelectric properties and multiferroic behaviors, characterized by the polarization-electric field, polarization current intensity-electric field, and magnetization-magnetic field curves, the composition with x=0.67 has maximum polarization, remnant polarization, maximum magnetization, and remnant magnetization of 15.0C/cm(2), 9.1C/cm(2), 0.33emu/g, and 0.14emu/g, respectively. In addition, the magnetocapacitance is evidenced by the increased relative dielectric constant with increasing the applied magnetic field (H). With H=8kOe, the composition with x=0.67 shows the largest values of (epsilon(r)(H)-epsilon(r)(0))/epsilon(r)(0)=2.96% at room temperature. The structure-property relationship is discussed intensively.