Site correction map derived from the slope of the topography is often well correlated with other independently-derived，regional-scale site-condition maps，but the latter maps vary in quality and continuity，and subsequently，also in their ability to match observed V30 S measurements contained therein (Wald et al，2007) ． This method has good application in the USA，as well as in Taiwan，Italy，and Australia． This paper elaborates on the theory and the method of generating shear-wave velocity maps and site correction amplification based on topographic slope，and studies the application in the 2008 Wenchuan MS8. 0 earthquake．