Abstract: The field programmable gate array (FPGA) technology, as a digital electronics technology different from CPU technology, is being applied more and more widely in nuclear safety instrumentation and control (I&C) system now. The architectures of FPGA based nuclear safety platform NuPAC and the reactor protection system based on NuPAC were presented, and improvements at the simplification of system design, independence and diversity of reactor protection system (RPS) architecture were analyzed in this paper. The advantages of FPGA technology to improve the determinism, security and sustainability of RPS system were analyzed. The system requirement analysis and the challenges related with requirements analysis were discussed. It will provide good reference for the development of other FPGA based safety I&C system in China.