The rapid development of Power System Protection put forward new requirements to relay constantly, the rapid development of electronic technology、computer technology end communication technology also inject new vitality for the development of relay technology continuously , therefore, the relay protection technology are developing and improving continuously. The task of protection is that remove fault components from the power supply system selectively, rapid, automatically, which can reduce the extent of damage to the lightest and, to a great, extend ensure trouble-free part of the rapid resumption recover normal operation. In addition, It can react the abnormal running state of electrical components, and according to the specific conditions of operation and maintenance and equipment bear capacity, it can issue a warning signal, reduce load or delay trip. This paper will analysis and research the relay protection status of power supply system of substation of Wuzhuang, which will draw theoretical foundation and setting principles of relay protection. on the basis of the existing hardware, this paper will optimist systematically the relay protection on the substation, in the end, the reliability, selective, rapid and sensitive of protection system of power supply system will be achieved the best condition.