Abstract: Two methods of synthetic fuzzy evaluation for site types are given based on the current Chinese Seismic Design Code for Buildings(GB 50011-2001). And a method for determining site characteristic period( the corner period of design response spectra) is also put forward. The membership function and coefficient g iven in this paper is used directly for engineering. The results by the different methods are similar on the whole, but somewhat different in the vicinity of the boundary of two neighboring site types. According to the results, the methods g iven in this paper are more reasonable.