Abstract:The control equipment of high-speed tunnel monitoring system has the characteristics of many kinds, large quantity, difficult to manage and easy to damage. The space in the tunnel is closed and the environment is bad. Once the high-speed tunnel monitoring system breaks down, it will harm the safety of the expressway, so the good fault diagnosis ability of the monitoring system is very important to the safety of the expressway. Combined with the flow and method of test design analysis of military products, this paper presents a set of fault diagnosis analysis and improvement methods for high-speed tunnel monitoring system, according to the system design architecture, the fault mode and impact analysis are carried out and the failure rate and severity of the fault are obtained. The BIT diagnostic circuit design is improved to increase its fault diagnosis ability and make the fault coverage rate of high fault rate and severity reach 80%, which provides a more efficient way of technology for the design and development of high-speed tunnel monitoring system.