The FAO is the first specialized agency in the UN system. It was supposed to be the Ministry of Agriculture in the UN, however, being dragged by the evolution of the international environment, the FAO's role and its status has been weakened. Once again, the world pays its attention to the issue of food security because of the resurgence of the food crisis in recent years. The existence of FAO attracts therefore people's attention. This article reviews the relation between the FAO and the food security by surveying the food security in different stage in the international context. And after the examination the other related UN organization, the author launches a serial of critics on the food security of the time being.