Two ceramic thick film electroluminescent (CTFEL) devices with or without Y2O3 which using the tetrad system PMN-PCW-PFN-PT ceramic thick film as insulator have been prepared. The CTFEL devices can be driven at 50 Hz between 30～110 Volts, and may be used as indicator or label lamp in safety electricity net. The electroluminescent performance of the EL devices with the different processing of ceramic thick film has been investigated in detail. It is indicated that the brightness of the CTFEL device with Y2O3 as insulator was higher than that without Y2O3 as insulator.