Based on the summarization of the status quo of the research both at home and abroad, the changing trend of the production of the main grain crops, covering the planting structure, seed structure and the trend of the per unit yields of garlic are analyzed. According to the comparative advantage theory, the comprehensive comparative advantages indices, which have been revised, can be used as the main research methods. By using the relevant data from 2000 to 2006, the scale comparative advantage, the efficient comparative advantage and the comprehensive comparative advantages of the main grain crops (wheat, millet, corn, soybean, rice and tuber crops) in each city of Henan Province are measured. The results show that among the main grain crops in Henan Province, only the wheat and the corn have comparative advantages; rice, corn, soybean and potatoes all do not have the scale advantages; the wheat, millet and the potatoes have obvious efficiency advantages while rice, corn and soybean have relatively weak efficiency advantages; wheat and corn have comprehensive comparative advantages, while rich, millet, soy bean and potatoes do not have the comprehensive comparative advantages. Combining with the current specific situation of Henan Province, the general situation faced by the production of main grain crops in Henan Province is analyzed specifically. In the end, suggestions on adjusting the structure of the main grain crops are put forward.