【目的】 害虫防治指标是害虫管理系统中进行优化决策的主要依据。本文研究了新疆棉区牧草盲蝽Lygus pratensis（Linnaeus）不同时期对棉花为害与棉花产量损失的关系，制定棉田防治指标，以期为新疆棉田牧草盲蝽防治提供理论和基础。【方法】 利用二次正交旋转组合设计，建立以蕾期、花期和铃期牧草盲蝽种群数量与棉花产量损失的回归方程，并结合棉花经济允许损失率，制定棉田蕾期、花期和铃期牧草盲蝽防治指标。【结果】 牧草盲蝽种群数量与棉花产量损失的回归方程：Y=12.906+5.273X₁+ 4.780X₂+2.365X₃+4.588X₁²+3.331X₂²+2.910X₃²。蕾期牧草盲蝽成虫为害对棉花产量损失的影响最大，其次是花期和铃期。牧草盲蝽防治指标，蕾期为12头/百株、花期为20头/百株、铃期为41头/百株。【结论】 本研究在棉花不同生育期的基础上，分别制定各个生育期牧草盲蝽防治指标，既简捷实用，又便于农民掌握，能更好的指导防治工作，同时可为新疆棉田牧草盲蝽防治提供理论基础。

 [Objectives]  Pest control indices are the main basis for optimizing decision-making in pest management systems. This study focused on the relationship between the amounts of damage caused by Lygus pratensis（Linnaeus）and cotton yield loss in different growth periods in Xinjiang. This control index was studied to improve L. pratensis control methods. [Methods]  Using the square regression, and orthogonal rotation, designs, the regression equation for the relationship between the L. pratensis abundance and cotton yield loss rate at the budding, flowering, and bolling stages, were determined. In combination with the economic loss to cotton producers, the control indices of L. pratensis during the budding, flowering, and bolling, stages were calculated. [Results]  The regression equation is: Y=12.906+5.273X₁+4.780X₂+2.365X₃+4.588X₁²+3.331X₂²+ 2.910X₃². The greatest reduction in cotton yield occurred at the budding stage, followed by the flowering stage with the least loss occuring during the bolling stage. The control indices of L. pratensis during the budding, flowering, and bolling, stages were 12 adults per 100 plants, 20 adults per 100 plants, and 41 adults per 100 plants, respectively. [Conclusion]  Control indices for L. pratensis can be calculated for different stages of cotton growth. This approach is practical, readily mastered by cotton farmers, and could provide a theoretical basis for the prevention and control of L. pratensi in Xinjiang.