Abstract: To provide scientific basis for the use of agro-climatic resources in Shifang and the reasonable arrangement of agricultural production, based on methods such as Mann-Kendall model and statistics as well as the monthly and yearly data of sunshine duration and the related factors in Shifang from 1961 to 2012, the author studied the variation characteristics of sunshine duration in that period. The result showed that: (1) the annual sunlight ratio demonstrated a significant reduction on the whole (tendency rate: -47.3 h/10 a), which was patently seen from the beginning of the 21st century and was mostly significant in summers with the tendency rate of -27.9 h/10 a; and the variation of monthly sunshine hours was characterized by a single peak; (2) the sunshine duration showed an abrupt change (significant reduction) in summers and winters as well as on a whole-year scale; (3) the annual sunlight ratio was positively correlated with the number of sunny days and the amount of precipitation, and negatively correlated with the average temperature; the significant reduction of sunshine hours at sunrise and sunset was relevant to the increase of obstacles and angle of elevation.