Abstract: This paper aims to assess grain production capacity of Northeast China and illustrate its capability to ensure national grain security being major grain production area. Through the researches of Northeast China on grain supply, grain structure and pressure to cultivated land, the paper concludes that: (1) the capability to safeguard national grain security has been enhanced and potential to increasing grain production is larger; (2) the planting structure face adjustment pressure from view of grain consumption structure; (3) the minimum area per capita of cultivated land and cropland pressure index has decreased 50 percent during the last 25 years; and (4) the cropland resource can effectively safeguard national grain security under the condition of grain yield per capita nowadays. Moreover, using system dynamics model, the paper simulates the grain production trend from 2010 to 2030 under different scenario, and provides some suggestions on the total and structural grain security according to the simulations' results