For the huge amount of raw data that were obtained during field data acquisition by the real-time kinematic global positioning system (RTK GPS) in structural health monitoring (SHM) system of the Nanpu Bridge in Shanghai, we finished lots of processing works and obtain x-coordinate , y-coordinate,z-coordinate time series of all 12 monitoring station points. The coordinate time series were treated as the multi-outputs of the dynamic system and used to build the state space model and ARMA model and spectrum estimations for the response. The analysis results were consistent with the results of test that completed when the bridge was opened in 1990 and results that forecasted by fine finite element (FE) model. The research illustrated that the state-space model and ARMA model were efficient tools for evaluation of performance of civil structures, and furtherly proved the possibility of building the prototype SHM that based on RTK GPS.