Abstract: In this paper, the authors described the spatial distribution model of sunshine duration in mountainous areas. With the aid of GIS technology, the authors took Xianju County of Zhejiang Province as an example, modeled the spatial distribution of monthly sunshine duration by using 1∶10000 DEM data with high spatial resolution and sunshine percentage data and validated the result. Validation determined that the simulated values were in agreement with the measured values, with a determined coefficient of 0.9435 (Xianju meteorological station) and 0.87 (Kuocangshan meteorological station). The temporal distribution characteristics of sunshine duration and its spatial variation with different altitude, slope and aspect were analyzed. The method and result have great significance for the research fields of agriculture, forestry and ecology in mountainous area.