Entering the acceleration period along with our country urbanization, the massive countryside surplus labor force shifts to the city, and large area of agricultural cultivated land was transferred to be non-agriculture use. The contradictory of grain supply and demand had the new change, and the grain safety has become to be the focus to stabilize social economy. This article utilizes method of marginal analysis to study the main construction of grain safety from the grain security essential factor angle, like: the grain production safety, grain supplies security, grain expense security. The results show that the grain security in urbanizing acceleration period is the function for grain production, grain supplies price, the farmer’s will for planting crops, and consumption habit of urban people. And the paper proposed the corresponding countermeasure for achieving the grain security.
