Based on the climatic data (from 1991 to 2000) of reprentaticve 25 counties in Shaanxi province, mean temperature, extreme temperature, precipation, and insolation in different period (year, April to October, July, August, September) were studied. According to these indexes, sum of active temperature (∑T), sum of effective temperature, hydrothermal coefficient (K) and relative illumination rate (Sc) were computed.The climatic characteristics of Shaanxi province were appraised,the climatic factors of influen...