Using the DEM(digital elevation model) data as input and giving an all-sided consideration on terrain factors influencing diffuse solar radiation(DSR),with topography openness model improved on,establishing monthly diffuse coefficient model,a distributed model for calculating DSR over rugged terrains is developed,and monthly DSR with the resolution of 1 km×1 km for the rugged terrains of China is generated.Results suggest that:(1)the topographical factors have relatively obvious effect on the spatial distribution of DSR;(2)the proposed model is proved to be able to treat volumes of data and is applicable to satellite image processing platform or GIS.