CaCu3Ti4O12 (CCTO) ceramics were fabricated by a wet-chemistry method. The effect of polyvinyl alcohol (PVA) addition on electric and dielectric properties of CCTO ceramics was investigated. After adding PVA, the grain-boundary resistivity and activation energy decreased, and nonlinear coefficient increased. All these results are relevant to their microstructures, more specifically, the secondary phase at grain boundaries. Though secondary phase was not observed from the X-ray diffraction patterns, the scanning electron microscopy images indicated that this phase could be controlled by PVA.