Cultivated land is the most basic element of food production. The “non-grain conversion” of cultivated land has generated a direct impact on food production in recent years. In the future，a number of trends regarding cultivated land use can be witnessed as follows. Firstly，the “non-grain” occupation of cultivated land will continue to increase. Secondly，the “non-grain” area of cultivated land will continue to expand. Thirdly，it is difficult to improve the soil quality of cultivated land in a short term. This change of cultivated land will not only affect the quantity of grain，but also affect the quality of grain. There are many reasons for the “non-grain conversion” of cultivated land，mainly including the behavior of government decision-making subjects，cultivated land contracting subjects，new management subjects and industrial and commercial capital subjects. Moderate and reasonable “non-grain conversion” of cultivated land can provide agricultural products other than grain and meet people’s growing diversified consumption demand. However，excessive “non-grain conversion” of cultivated land will have a serious impact on food security，especially in the main grain production areas. Therefore，there is a need to strictly control the use of cultivated land，strengthen the coordination between departments，and improve the cultivated land protection and compensation system to prevent the “non-grain conversion” of cultivated land.