Abstract: The effects of foliar spraying uniconazole (S3307) and kinetin (KT) on carbon metabolism of maize leaves and yield were studied in order to provide theoretical foundation for maize production. In the filed experiment, using‘Demeiya 1’and‘Demeiya 2’as test materials, S3307 and KT was sprayed at 7 leaves expansion stage, water was sprayed as control. The effects on the carbon metabolism of maize leaves and the yield were studied. The results showed that S3307 and KT increased panicle weight, grain weight, number of rows, kernels per row and single grain weight, and then raised the grain yield. The regulating effect of KT treatment on the yield of‘Demeiya 1’was better than that of S3307 and the regulating effect of S3307 treatment on the yield of‘Demeiya 2’was better than that of KT. After 21-30 days of spraying regulators, the two regulators decreased the starch content and starch amylase activity. The starch content and amylase activity of‘Demeiya 1’ was decreased by the range of 0.16%- 31.10% and 7.58%- 45.83% , respectively. The starch content and amylase activity of‘Demeiya 2’was decreased by the range of 2.68%- 42.01% and 3.97%- 39.82% , respectively. After 21 days of spraying regulators, the order of sucrose and soluble sugar contents in leaves of the two varieties was KT＞S3307＞CK. Compared with the control, the sucrose and oluble sugar content of ‘Demeiya1’increased by 84.64%, 31.28%, 67.38% and 52.74% by foliar spraying KT and S3307, respectively; the sucrose and soluble su ar content o‘f Demeiya2’increased by 14.21%, 3.92%, 49.34% and 37.50% by foliar spraying KT and S3307, respectively. S3307 and KT could significantly enhance physiological activities and delay the senescence of maize leaves during middle- late growth stages. Thereby, they were effective to increase the yield of maize.