In order to effectively suppress the possible common mode failure of computer system software and hardware, analysis is made to dissimilar redundant technology and its redundant architecture and the number of redundancy based on the redundancy technology.The design and implementation of a dissimilar dual redundant alarm computer are discussed from such aspects of the hardware/software architecture design, hot-standby switching logic and so on.The fault tree analysis method is used for analyzing and calculating the reliability of the system based on the experimental data.The results show that: The use of dissimilar dual redundant technology can effectively suppress the common mode failures of software and hardware system, and improve the reliability of the airborne warning computer system to 0.999 97.