The health monitoring of civil engineering structures isan important research field, which covers various areas, suchas data acquisition system, signal processing, structure analysis. In thispaper, the necessity and urgency to implement structural health monitoringin civil engineering are discussed, including the concepts, structures andapplications of the structural health monitoring system. Allsubsystems are analyzed with respect to their functions, characteristics andimplementations. The theories, methods and mechanical issues of thesubsystems are emphasized. Finally, some promising researchsubjects in the area are pinpointed.