Abstract: Aiming at the situations of coal mining badly damaged farmland,gangue covered farmland in large quantities and serious phenomenon of "three unders" pressed coal in the eastern plains mining area of our country.This paper analyzes the ways of protecting farmland by backfilling with gangue,and researches the feasibility of many ways and the models of protecting farmland area.In view of China's national conditions,with mining under buildings as the breakthrough point,this paper proposed a model of protecting farmland by backfilling with gangue which is suitable for China's national conditions on the base of collaborative relationship of gangue quantity,area of protected farmland and replacement of dull resources amount.Finally,the research is applied in engineering examples.