Abstract: To reveal the effect of spatial-temporal variation of cultivated land on grain production capacity, taking northeast grain main production area Bayan county as study area, land detailed survey database in 1991, land use changes database in 2006 and SPOT5 image in 2009 as the basic information source, and the grain yield per hectare and other statistics as the basic data source were used to analyze in the study. Based on RS and GIS technologies, land comprehensive index evaluation method was used to analyze temporal and spatial variation of the quantity and quality of cultivated land in study area, and its effect on grain production capacity was also studied. The results showed that the quantity of cultivated land in study area increased from 1991 to 2009. The conversion from cultivated land to non-cultivated land mainly occurred in forest land and other land. In 1991-2006, the third grade of cultivated land area were the most increased, the first grade was least increased; For the reduction of cultivated land area, the second grade and the third grade were most reduced, the first grade was least reduced. In 2006-2009, the second grade of cultivated land area were the most for increase, the first grade was least increased; For the reduction of cultivated land area, the third grade was most reduced, the first grade was least reduced. The second grade cultivated land which is located in the northern hills plain agricultural area had the largest effect on grain production capacity, and although the third and fourth grade cultivated land were 50% of the total cultivated land area, grain production capacity was restricted by the natural and soil factors.