Good controlling effect to monocotyledon and dicotyledon weeds were achieved by spraying 50% Acetochlor, 2,4-D and Prometryne EC between sowing and seedling in corn field. The controlling effect of weed quantity was 78.68% to 87.49% in 45 days, while the controlling effect of weed fresh weight was 77.07% to 85.39%. Controlling effect was improved steadily as more chemical applied. All treatments increased the yield ranging from 11.79% to 15.18%.