The correlation relationship between conductivity and luminance intensity in ZnGa2-xInxO4 phosphors for various indium mole fractions was investigated. The cathodoluminescence spectra showed that the tuning range of the color emission was between 340 and 420 nm, and the X-ray diffraction curves indicated that ZnGa2-xInxO4 with the indium mole fraction between 0 and 0.0006 formed a single phase, The increase of the conductivity in the ZnGa2-xInxO4 enhanced the luminance intensity. The present observation provides information on the optical, structural, and electrical properties useful for improving device efficiencies in the field emission displays fabricated utilizing ZnGa2-xInxO4 phosphors.