Aiming at the problem of low efficiency and poor processing quality for electrical discharge machining（EDM）of insulated ceramics, an EDM pulse power supply based on field programmable gate array（FPGA）was developed by analyzing the gap discharge state of insulating ceramics. The power supply can realize the equal pulse duration of lowresistance spark discharge and highfrequency packet pulse mode for suppressing harmful discharge. In terms of the hardware, the pulse power supply was designed in modular, which was composed of FPGA-based main vibration module, MOSFET power amplification module with LCD buffer circuit, and the gap discharge state detection module based on 4 threshold voltage and current. The results show that compared with the conventional pulse power supply, by using the developed pulse power supply, the lowresistance spark discharge rate can be effectively improved and the harmful pulse discharge rate can be effectively suppressed; the processing speed is 0.48 mm/min, which is increased by 33%; the relative loss of the electrode is 132%, which is reduced by 16.9%; the surface roughness is 4.6 μm, which is reduced by 22%; the pore edge and the pore wall have no significant micropore. The developed pulse power can effectively improve the processing efficiency and processing quality of insulated ceramics.