In Japan, Bridge is an important part of public transportation infrastructures. As a result, the monitoring of bridge health is accordingly vital important for the government and related institutions. In bridge diagnoses system, we develop a wireless sensor network to measure and gather the vibration data of bridge. The problem is: in past field bridge diagnosis experiment, node failure and data packets loss always occurred in the WSN. Furthermore, when we deploy all the nodes of WSN to bridge in the first time, it is always difficult to set the location of nodes in order to ensure the quality of link is extremely reliable. In order to solve above mentioned problem we propose a distributed data aggregation active monitoring method and a distributed localized decision monitoring method. Based on the two methods we build a self-health monitoring system for WSN: DLDMS (Distributed Localized Decision Monitoring System). We apply this system to the field experiments at Kitakyushu city in Japan and successfully obtain the health status of WSN.