Since 1978, grain production in China has increased significantly and food production has more than doubled from 304.7 million tons to 616.5 million tons. Among them, corn production greatly increased from 55.95 million tons to 219.55 million tons in 2016, which is about 4 times lager than that of the previous year. The net effect of each policy is introduced by introducing the assumption-based monopoly liability system and the market price, and the quantitative basis of whether the policy is continuously implemented in the future is presented.