The β-sialon:Eu2+ phosphor has superior luminescent properties as an excellent green down-conversion material for white light-emitting diodes. To take advantage of its high chromaticity and apply it to field emission displays (FEDs), the drawback of its electron insulation that impedes the electron transmission when excited by e-beam needs to be solved. In this work, a facile method was adopted to coat conductive In2O3 on the surface of β-sialon:Eu2+ phosphor, and the influence of In2O3 coating on the cathodoluminescent properties was investigated. The results show that the In2O3 coating contributes to charge elimination and significantly improves the cathodoluminescence (CL) of β-sialon:Eu2+. Under 19 kV/1.0 nA e-beam excitation, the In2O3 coated sample shows CL intensity about four times higher than that of the uncoated β-sialon:Eu2+. Moreover, no luminescence saturation occurs in coated β-sialon:Eu2+, indicating that the In2O3-coated β-sialon:Eu2+ would be a promising green emissive material for full-color FEDs.