Wireless sensor network are deployed today to monitor the environment, but their own health status is relatively opaque to network administrators, in most cases. In bridge diagnosis system, we develop a wireless sensor network to gather the vibration data of bridge. In past field bridge diagnosis experiment, node failure and data packets loss always occurred in the WSN and can not be detected. It causes some collected data is broken and cannot be used to analyze the health status of bridge. Furthermore, in field experiment it is always difficult to set the location of nodes in order to ensure the quality of link is good. In this paper, we consider the problem of monitoring the health of nodes, the quality of links and the healthiness of bridge diagnosis data from active end-to-end measurements in wireless sensor networks. Our system, DAMS (Distributed data Aggregation active Monitoring System), provides failure detection and symptom alerts, while being frugal in the use of energy and bandwidth. In order to improve the performance of active monitoring method we use distributed data aggregation to reduce the amount of communication and energy consumption. The monitoring system contains three functions, monitoring the health of nodes, monitoring the link quality and monitoring the healthiness of bridge diagnosis data. Key performance measures of this system include high detection accuracy (low false alarm probabilities), high responsiveness (low response latency), low energy consumption and low complexity. We debug the system in the wireless sensor network developed for bridge diagnosis and obtain the result in field experiment.