Abstract: Considering the influence of terrain factors such as gradient and slope direction on sunlight and radiation,a GIS model which fits to mountain areas in the East and Central China was established through ameliorating the formula of slope sunlight and radiation calculation.Annual sunlight times and solar global radiation in Hunan Province were calculated using this model,based on its 500m×500m grid geographical data with Citystar GIS.The results showed that the sunlight resources and their characteristics in the mountain areas could be well explained because some terrain factors such as gradient and slope direction were taken into account.The model had been proved to be a practical model.

Key words: Sunlight, Sunlight, Radiation, GIS Model, Terrain