This paper describes the implementation of a continuous structural health monitoring system to a building (National Center for Research on Earthquake Engineering) in Taipei basin, Taiwan. This seismic monitoring system is primarily designed by using pre-seismic event data, post-seismic event data and seismic event data for online and post-earthquake safety assessment of the building. Besides the design of online monitoring system in this building, the essential component of the system is the implementation of the automatic data analysis tools and software packages to extract the building vibration characteristics and dynamic features for building safety evaluation. Integration of data processing modules, system identification software and simple damage detection mechanism, the assessment of the building's condition before and after each seismic event can be reported immediately. Through such online analysis of the building response data, the event-by-event information and the time-varying dynamic characteristics of the building can be extracted, building healthy condition is created which can support the decisions for necessary maintenance and rehabilitation of the building.