Abstract: Background and Objective: Soil tillage and weed management are two factors that can be manipulated to increase the yield of corn. The objectives of this experiment were to study the application timing of atrazine and mesotrione mixture for weed control in no-tillage corn. Materials and Methods: The field experiment was organized in a split-plot design with 2 factors, the main plot was land preparation including no-tillage using glyphosate for land clearing, no-tillage using paraquat and conventional tillage, the sub-plot was the application timing of premixed formulation of atrazine and mesotrione which was 2, 3, 4 and 5 weeks after planting (WAP).Results: Using glyphosate is an appropriate measure for land clearing in the no-tillage system. The premixed formulation of atrazine and mesotrione applied at 2 and 3 WAP performed the highest efficacy of 95-100%. However, weeds were regrowth faster when the application was carried out at very early postemergence (2 WAP) indicated with the heaviest weeds biomass. The best growth and the highest yield of corn were found when the application time of the atrazine and mesotrione mixture was at 2 and 3 WAP.Conclusion: Glyphosate is an appropriate measure in no-tillage corn and the application time of 2 or 3 WAP of the atrazine and mesotrione showed the highest efficacy on weeds, the better growth and the highest yield of corn.