Sky and terrain factors are elements influencing the Diffuse Solar Radiation(DSR) over rugged terrain.By using DEM data and the extraterrestrial solar radiation model and the terrain openness model,influences of terrain factors on the diffuse solar radiation are comprehensively evaluated.By using the horizontal diffuse solar radiation model simulated by routine meteorological observation data,influences of sky factors on DSR are evaluated.Thus,a model to calculate the diffuse solar radiation over rugged terrains in Zhejiang province was developed and the monthly spatial distribution of DSR was calculated.The results show that:the geographical and topographical factors,the monsoon influence and the atmosphere transparence exert effects on spatial distribution of DSR;the annual DSR presents a decreasing trend form south to north;the order of seasonal DSR is summer>spring>autumn>winter;the maximum(minimum) DSR lie in the open areas(shaded areas) and has little to do with the slope and aspect.It varies in different seasons.The results can provide data for researches of climate change and environmental resources.