In order to determine the optimal foliar spraying amount of selenium for improving the sugar content in grain and promoting the safe production of selenium-enriched waxy corn,two-factor split-plot design was used to study the physiological characteristics and the contents of sugar and selenium of two maize varieties Caitiannuo 1965 and Jinnuo 20 under five selenium levels.The results showed that as the spraying amount of selenium on the leaves increased,the POD activities,contents of GSH,chlorophyll,soluble sugar and sucrose of CTN1965 and JN20 all increased first and then decreased,which were the highest in the treatment with 45 g/ ha selenium,increased significantly by 47.94%,149.80%,49.86%,30.81%,29.33% and 49.16%,115.35%,73.12%,28.08%,21.57% compared with control without selenium;MDA content decreased first and then increased,which was the lowest in the treatment with 45 g/ha selenium,decreased significantly by 41.51% and 40.96% compared with control;selenium content of grain increased,which was the highest in the treatment with 90 g/ha selenium,increased by 1 046.06% and 908.76% respectively,and exceeded the safety standard of selenium-enriched corn.Through equation fitting,the safety upper limit values of spraying amount of selenium of CTN1965 and JN20 were 63.96 g/ha and 89.53 g/ha respectively.Considering the physiological characteristics and the contents of sugar and selenium in grain, the optimal spraying amount of selenium of CTN1965 and JN20 was 45 g/ha, which could reach the standard of selenium-enriched corn.