The computer relay protection facility takes on the role of judging the failure of electric power, at the same time it gives message to run personnel and communicates with other devices, so it must be a highly reliable measurement and control system with high performance. The paper analyses the composing of computer relay protection facility based on standard bus and mainly introduces the steps of improving the reliability of the system. The computer relay protection facility based on such a principle has been developed and applied to the Central China Electric Power System.