Abstract: Thornthwaite’s method on calculating PE and climatic classification has been applied on computing data from 671 climatological observation stations in China. A geographic regression model of potential evapotran-spiration is resulted as APE=2037.98—18.8308 LAT—4.5801 LONG—0.157861ALT. The resulted APE and moisture index, Im are closely correlated with the major vegetation types and their distribution pattern in China. The bounds of thermal coefficient (APE) for the vegetation in China fits in quite well with which in North America, but the Im is evidently lower than there. That just is a reflection of the ecological characteristics for vegetation of China. The research makes known that the method should have a broad prospect for application in the country.