Abstract: 【Objective】 To study the synergistic effects of spraying adjuvants on control of gramineous weeds in cotton field in the hope of providing data basis for the application of herbicide scientifically. 【Method】 With the pot and field experiments, the control effect of quizalofop-P-ethyl EC on the gramineous weeds such as Digitaria sanguinalis and Eleusine indica was compared by adding additives on the basis of conventional dosage, 20% reduction and 40% reduction. 【Result】 In the pot experiment, adding adjuvants Foxy SG and Fieldor Max EC under the conventional dosage, the fresh weight control of quizalofop-P-ethyl EC on Digitaria sanguinalis and Eleusine indica increased by 1.75%-5.78%, when the conventional dosage was reduced by 20% and 40%, the control effect of adding adjuvants increased by 7.95%-10.54% and 21.62%-41.63%, respectively. The synergism of Fieldor Max EC was significantly better than Foxy SG, and there was no significant difference between the control effect of adding Fieldor max EC and 40% reduction of conventional dosage. In the field experiment, the result was consistent with pot experiment. The control effect and fresh weight control effect of conventional dosage of quizalofop-P-ethyl EC were increased by 0.83%-4.19%, when Foxy SG and Fieldor Max EC added under conventional dosage and 20% reduction and 40% reduction of quizalofop-P-ethyl EC, the control effects were increased by 1.08%-8.68% and 12.06%-37.74%, respectively. The synergism of Fieldor Max EC was significantly better than that of Foxy SG, and there was no significant difference between the control effects of adding Fieldor max EC or 40% reduction. 【Conclusion】 The two kinds of adjuvants can significantly improve the herbicidal activity of the quizalofop-P-ethyl EC, and adding adjuvants can solve the problem of control effect decline after reducing the use amount of herbicides. Adding efficient adjuvants in the herbicides is an effective way to achieve the aim of reduction and synergism.