There are still 2127.79kg,966.06kg and 290.45kg potential respectively for the increase of corn yield per Mu in China according to the average theoretical light-temperature yield,achievable biological limit yield and variety regional trials yield in recent years.Experts' participatory appraisal shows that the main constraints for the realization of corn yield potential are cultivation and planting problems such as extensive cultivation and poor tillage management,nonstandard techniques,etc.On the other hand,there are drought and other unfavorable ecological and climate conditions,too many corn varieties etc.Therefore,both the improvement of production techniques and popularize science and technology among farmers are also important aspects for the government in making policy to achieve higher corn yield.