Abstract： Strong motion observation is very important for the nuclear power plant, High-speed Rail and other important project. In this paper, the amplitude, frequency spectrum, duration of ground motion parameters are all considered, innovation land have put forward the new method of seismic intensity which is synthesized by three components, through the analysis of instrumental intensity method of the U.S. Geological Survey (USGS) and the Japan Meteorological Agency. This method is verified by the Wenchuan earthquake, which may provide useful references to seismic intensity rapid assessment.