High and large capacitance base–metal–electrode multilayer ceramic capacitors (BME MLCCs) for future application require much thinner dielectric layers (<l μm) than ever before, which means that grain size uniformity of BME MLCC powder should be effectively controlled. In this paper, high-performance nanosized BME MLCC powder was developed by a novel and convenient aqueous chemical coating method. Various kinds of dispersants were used to disperse BaTiO3 particles in aqueous solutions. Poly(acrylic acid–comaleic acid) was found to be the best for dispersing. BaTiO3 particles were well coated by adding the doping elements into the uniform BaTiO3 slurry in the form of inorganic solutions and organic solutions under an appropriate pH value. Thermogravimetric analysis, transmission electron microscopy, and energy-dispersive spectroscopy were utilized in the study of calcining, microstructures, and element analysis. The dielectric constants of the ceramics at room temperature could reach 2100, with low dielectric loss <1.0% and high insulation resistivity ∼1012 Ω·cm. The average grain size is as low as about 130 nm.